Feats are a precious resource: most characters get seven over the course of their entire career, with humans getting eight and fighters getting eleven more... but at the dire cost of having to be a fighter. That's not even taking feat taxes into account, with many of the more desirable prestige classes necessitating one or more feats that are otherwise of little to no use.
So how can you ensure your feats are working hard enough for you? In particular, more specific feats might have a strong effect, but they run the risk of being useless in most situations. Well, there is a rather simple way to not only get more feats, but to get them on-demand, picking up whatever suits the situation as you need it.
There's a little gem in the Spell Compendium called heroics - a level 2 sorcerer/wizard spell that lets you grant the subject a single feat off the list of fighter bonus feats for 10 minutes per level. Even at minimum level, that's half an hour to make use of your new feat. Having to be a fighter bonus feat is indeed a big restriction, especially from your viewpoint as a spellcaster - no crafting, no metamagic and nothing along the lines of spell focus, obviously. But if you look, you might be surprised by how extensive the list really is, often with bonus feats appended to it with every book. In particular, versatile feats that grant you choices gives you a 'feats-within-feats' situation that can be tooled to suit any character.
Heroics isn't an especially finicky spell: you just need to select a feat on the fighter list, and meet the prerequisites. What isn't entirely clear is whether multiple castings of heroics stack - each providing a different and non-mutually exclusive effect - the way energy resistance does. I'd say they ought to, but your mileage may vary. If they do, that lets you dig deep into feat trees with multiple castings, which is definitely interesting if not a great use of spell slots.
Generally speaking, the best target for heroics is the melee bruiser in your party. He or she is going to have the stats and specialization to both fulfill prerequisites more readily and to take advantage of the man-with-stick-oriented effects on offer from the fighter list. They'll definitely appreciate not having to waste feat slots on situational options, as well as the opportunity to test-run dubious ones. However, ranged combat feats might be more likely to help the party sneak, and anyone can appreciate a defensive feat. If you're a straight caster, no amount of bonus feats will turn you into a combat beast, so focus more on utilitarian choices when targeting yourself.
Another thing to keep in mind is that if you target yourself, you can share the spell (and thus the feat) with your familiar. I don't know if I can rightly say whether or not you and your familiar need to select the same feat, that may be up to a DM call. You can also just cast it on your familiar or on summons (bruisers like earth elementals are particularly tempting) to give them feats. Casters without familiars can still spread the fun around with the Reach Spell & Chain Spell metamagic feats (or by taking levels in War Weaver) to share the bonus feat with the whole party and all of its sundry cohorts, hirelings, pets, familiars, animal companions, minions, summons and so on.
Heroics is arcane-only, appearing only on the wizard/sorcerer list, but as a level 2 spell, it is a candidate for anyspell. Clerics with a penchant for combat could certainly appreciate another feat or two that helps to that end, and they're of course the class with the easiest access to cheap Persistent spells. Heck, you could then cast triadspell on the slot from anyspell, which can get you a whole lot of bonus feats through tripled castings of Extended Persistent heroics.
Now then, thankfully the list of fighter bonus feats is very large, making heroics a versatile spell. Indeed, so large that it would be overwhelming to have to skim through the list every time you need to pick what you want. Thus, I've compiled some of the more intriguing standouts, grouped in a few broad categories for what you might need in some situations. Note that the feats listed here are slightly more geared towards the caster using heroics on himself, since what the fighter wants will be dependent on their combat style. Prerequisites for each feat are listed in parentheses.
Weapon Finesse (BAB +1): Using Dexterity instead of Strength on light weapons won't make you a damage-dealing machine, but it can often raise your attack rolls by two or three points.
Subduing Strike: Removes the penalty for dealing nonlethal damage. Good for taking prisoners.
Adaptable Flanker (Combat Reflexes, Vexing Flanker, BAB +4): You and your familiar can flank a foe even if your familiar's sitting on your shoulder.
Vexing Flanker (Combat Reflexes): The bonus from flanking is +4 instead of +2. Might as well help the sneak attacker do his thing.
Blind-Fight: Nice if you're surprised by invisible foes. Doubles your chance of hitting them and removes their bonuses to attacking you. Plus, you can move around in the dark more readily.
Chosen Foe: +1 to attack rolls and AC against a single foe, but a -2 penalty to attacks and AC against all other foes. Good to pull out for fighting a single powerful opponent.
Mage Slayer (Spellcraft 2 ranks, BAB +3): +1 bonus to Will saves, and spellcasters you threaten can't cast defensively. Note that it also reduces your caster level by 4, making this better suited for the non-casters in the party, though they may have trouble getting Spellcraft ranks. At least it's temporary!
Pierce Magical Concealment (Con 13, Blind-Fight, Mage Slayer): You ignore concealment and miss chances from magical sources, as well as mirror image. Reduces your caster level by 4.
Pierce Magical Protection (Con 13, Mage Slayer): You can make attacks that ignore AC bonuses granted by spells, and then subsequently dispel said spells. Reduces your caster level by 4.
Spectral Skirmisher (BAB +6): Gives you extra advantages while invisible, including being harder to detect with Listen and getting an attack of opportunity on anyone trying to hit you.
Weapon Supremacy (Weapon Focus, Weapon Specialization, Greater Weapon Focus, Greater Weapon Specialization, Melee Weapon Mastery, Fighter level 18): I know what you're thinking. Look at that list of prerequisites! How can there be a character in existence that qualifies for Weapon Supremacy but hasn't taken it?! Well, as much as I advise against it, this is basically the only way for a 20th level Warblade that qualifies to get the feat before epic levels. Just thought I'd mention.
Point Blank Shot: +1 to attack & damage on ranged attacks within 30 feet. This includes ranged touch spells.
Precise Shot (Point Blank Shot): You suffer no penalty for firing ranged attacks into melee.
Deadeye Shot (Point Blank Shot, BAB +4, sneak attack or skirmish, Precise Shot): If you ready an action to attack someone when they're hit by an ally's attack, your ranged attack ignores their Dexterity bonus to AC. Once again, applies to ranged touch spells.
Ranged Disarm (Dex 15, Point Blank Shot, Precise Shot, BAB +5): You can disarm foes up to 30 feet away with a ranged attack.
Ballista Proficiency: If you're going to be using a ballista, generally it's in a fight you'll see coming.
Close-Quarters Fighting (BAB+3): You get an attack of opportunity when something tries to grapple you, even if it has Improved Grab. The damage you deal with said attack is added to your grapple check.
Combat Panache (Bluff 8, Intimidate 8, Perform 8): Tactical feat that gives you defensive maneuvers performed with Charisma-based skills. Sneering glower lets an Intimidate check apply your Charisma bonus as a penalty to a foe's attack rolls, potentially making the Sorcerer very hard to hit. Fortuitous Tumble can make a foe mistakenly strike his ally with a good Bluff check.
Constant Guardian: You can take a -2 penalty to attacks to give a +2 dodge bonus to the AC of an ally within 10 feet. Chances are your familiar wasn't making tons of attack rolls, anyway.
Dutiful Guardian (Constant Guardian): You can swap places with a nearby ally when they're attacked.
Deflect Arrows (Dex 13, Improved Unarmed Strike): Once per round, you can deflect a ranged weapon attack that you are aware of.
Block Arrow (Dex 13, Shield Proficiency): Same as Deflect Arrows, but you need a shield instead of a free hand.
Improved Toughness (+2 base Fortitude save): Grants +1 HP per hit die. Bear's Endurance lite!
Shadow Striker (Hide 12, Move Silently 12): Tactical feat that lets you make Hide checks even in the thick of combat. Helps you avoid notice and even score sneak attacks.
Tunnel Fighting (BAB+1): You don't take a penalty to attack rolls or AC while squeezing through a tight space. Could be useful if you're ambushed in a compromising situation.
Combat Focus (Wis 13): After you make your first attack in an encounter, you get +2 to will saves.
Combat Vigor (Combat Focus, Wis 13, BAB +9): Gain fast healing 2 while in combat focus. Might be able to use this to farm HP off beating up your summons or random weak encounters.
Improved Initiative: Anyone can appreciate +4 initiative. Nerveskitter's better, but this will last longer. Besides, you prepared a spell that can do a whole lot more than just improve initiative.
Danger Sense (Improved Initiative): Once per day, you can reroll an initiative check.
Combat Intuition (Sense Motive 4, BAB +5): Lets you determine roughly how much HD a foe has with a sense motive check as a free action. Also, you get a +1 bonus to hit anyone you hit last round.
Blade Meditation (Concentration 1, BAB +4, one maneuver): You get a +2 bonus to one of tumble, intimidate, concentration, balance, sense motive, hide, jump or diplomacy.
Exotic Weapon Proficiency (BAB +1): You may remember how much this can do for you. This could go under literally any category, with ways to provide offense, defense, utility and combat actions... assuming you have the right weapon on hand, anyways.
Combat Awareness (Blind-Fight, Combat Focus, Wis 13, BAB +12): While in combat focus, you know the current HP of each adjacent creature. Can also grant 5-foot blindsight.
Giantbane (Medium or smaller, Tumble 5, BAB +6): Tactical feat that's useful for fighting larger foes. Can give you +4 to attack rolls and AC. Also can climb a foe two sizes larger than you to 'ride' them and make it harder for them to hit you.
Daunting Presence (Cha 13, BAB +1): As a standard action, you can make an opponent within 30 feet shaken for 10 minutes if they fail a Will save.
Goad (Cha 13, BAB +1): As a move action, you can force an opponent that threatens you to be unable to make melee attacks against anyone but you for one round if they fail a Will save.
There are plenty of options to pick from with a casting of Heroics, but there are two feats that I feel virtually overshadow all other choices: Martial Study, and Martial Stance.
Maneuvers are spells for sword-swingers; fighting game moves that let you accomplish an impressive variety of things, even outside of combat. Need to get to a ledge 500 feet up? Remove an adamantine door? Track someone? Immunity to fire? Any one of these and more are possible from a casting of heroics, all thanks to Martial Study.
For the average target, you grant them a low-level maneuver with no prerequisites, which they can use once per fight so long as heroics lasts. The best targets, of course, are martial adepts who already have a full initiator level and plenty of maneuvers - you can grant them any maneuver they qualify for as needed. Being able to pull out Pearl of Black Doubt against a horde of mooks, or Mind Strike against a cleric, gives what may already be the most versatile melee classes even more utility to work with. As a wizard/sorcerer yourself, you're not going to be bothering with any sort of damaging maneuver, but there are a decent number of low-level tricks you can use for defensive or utilitarian purposes.
Whether multiple casting of heroics stack is of paramount importance considering Martial Stance, which requires a maneuver known (ergo, another casting to have granted you Martial Study.) There's a good chance you'll get more value out of the stances, since they're passive benefits that last as long as heroics does, rather than a once-per-encounter ability. Of course, you can also take multiple Martial Stances to take maneuvers that have prerequisites - two casting can give your familiar White Raven Tactics. If they don't stack, though, the trick to qualifying for stances is to use the items in Tome of Battle that grant you a single maneuver (White Raven Crown, etc.) 3000 gp is a pittance to be able to qualify for White Raven Tactics.
Gathered here, then, is a list of some of the more useful maneuvers. I only included up to 3rd level maneuvers, since if you're not a martial adept, you'd need to be level 14 or higher to even qualify (and if you are one, you can qualify for basically anything you want.) The first tier of maneuvers listed can be granted with a single casting of heroics; the second tier requires a second casting or an item in order to have the necessary prerequisite.
Burning Blade (Desert Wind 1): All melee attacks deal +1d6 points of fire damage, +1 point per initiator level. Solid on pouncers, TWFers and summons with a claw/claw/bite routine, who can generate many attacks in one turn.
Distracting Ember (Desert Wind 1): Summons a small fire elemental until the end of your turn. Can be used for flanking (you're welcome, rogues,) setting things on fire, checking for traps, illumination... whatever you can think of with 6 seconds of fire.
Death Mark (Desert Wind 3): You make an attack which also deals 6d6 fire damage in a spread outward from your foe - the larger your opponent, the larger the spread. The dream against "big boss with his army of mooks."
Vanguard Strike (Devoted Spirit 1): You strike a foe and give all allies a +4 bonus on attack rolls against them until your next turn. A boon in large parties, and it helps out touch spells, too.
Moment of Perfect Mind (Diamond Mind 1): Make a Concentration check instead of a Will save. No need to bother for you, the caster, but can help the fighter be proactive against those dreaded Will saves.
Action Before Thought (Diamond Mind 2): Make a Concentration check instead of a Reflex save. As a spellcaster, your Concentration modifier is probably sky-high.
Mind over Body (Diamond Mind 3): Make a Concentration check instead of a Fortitude save. What 'bad saves'?
Wall of Blades (Iron Heart 2): When you're attacked, make an attack roll with your melee weapon and use that result instead of your AC. Note that this also works against touch attacks, such as rays.
Counter Charge (Setting Sun 1): You can force an opposed Strength or Dexterity check on anyone who charges you to cancel their attack. Charging is common enough that this is a good defense to have in your back pocket.
Cloak of Deception (Shadow Hand 2): As a swift action, you turn invisible for the rest of your turn. Hellooo, sneak attacks!
Shadow Jaunt (Shadow Hand 2): Teleport 50 feet as a standard action.
Shadow Garrotte (Shadow Hand 3): Make a ranged touch attack against an opponent for 5d6 damage and a Fortitude save against becoming flat-footed. Decent damage, and plays nicely with the party rogue.
Leading the Attack (White Raven 1): Same as Vanguard Strike, just a different school.
Flame's Blessing (Desert Wind 1, stance): Grants resistance to fire based on your ranks in Tumble. With 19 or more ranks, you have fire immunity.
Fan the Flames (Desert Wind 3): Deal 6d6 fire damage as a ranged touch attack on one foe within 30 feet. Most people are pretty startled when your familiar can spit fire.
Holocaust Cloak (Desert Wind 3, stance): Anyone who hits you with a melee weapon takes 5 points of fire damage. Can add up when stuck on the party tank, especially if you're fighting swarms or monsters with tons of natural attacks.
Zephyr Dance (Desert Wind 3): Gain +4 AC versus a single attack as an immediate action.
Iron Guard's Glare (Devoted Spirit 1, stance): Foes within reach take a -4 penalty on attack rolls against allies. Protect yourself by buffing an ally or summon.
Martial Spirit (Devoted Spirit 1, stance): With each successful attack, you or an ally within 30 feet can heal 2 points of damage. Can be used to farm HP from summons or nonthreatening monsters.
Revitalizing Strike (Devoted Spirit 3): Make an attack, and heal 3d6 damage +1 per initiator level to an ally within 10 feet (including yourself.) Who said wizards can't heal?
Thicket of Blades (Devoted Spirit 3, stance): Foes you threaten who try to move (including a 5-foot step!) provoke an attack of opportunity. Combine with the Stand Still feat, and the party tank can lock down the battlefield nearly as well as you can.
Emerald Razor (Diamond Mind 2): Make a single melee attack as a touch attack. If you've got a two-handed weapon and Power Attack, a single attack is all you'll need.
Pearl of Black Doubt (Diamond Mind 3, stance): Every time a foe misses you, you get +2 AC until your next turn. Excellent against hordes of minions.
Absolute Steel (Iron Heart 3, stance): You get +10 speed. If you move at least 10 feet in a turn, you get a +2 dodge bonus to AC until your next turn. Two things casters like: moving away and not getting hit.
Iron Heart Surge (Iron Heart 3): You should remember this; it's one of The Big Ones. It gives you +2 to attacks rolls for the turn, and you immediately end one "spell, effect, or other condition currently affecting you and with a duration of 1 or more rounds." You can undo being blinded, exhausted, sickened, flat-footed, on fire, or about a zillion other things. You can even end a web or anti-magic field - not just render yourself immune, but end the effect entirely. Two castings of heroics lets you remove negative levels long before restoration is online, and it saves 100 gp on the material component. This single maneuver alone at least doubles what heroics is capable of accomplishing.
Punishing Stance (Iron Heart 1, stance): All melee attacks deal +1d6 damage, but you take a -2 penalty to AC. Good for Totemists, TWFers and other characters with lots of attacks.
Step of the Wind (Setting Sun 1, stance): You take no penalty for walking on difficult terrain, and you get a bonus to attack rolls, trip and bullrush attempts against foes on difficult terrain.
Giant Killing Style (Setting Sun 3, stance): +2 attack bonus and +4 damage bonus against foes larger than you. Perfect example of a situational effect that's strong but not worth learning permanently.
Assassin's Stance (Shadow Hand 3, stance): Gain +2d6 sneak attack damage. The party rogue's wet dream, but also just plenty of bonus damage for anyone in any old flanking situation.
Dance of the Spider (Shadow Hand 3, stance): spider climb at will - no need to prepare that spell ever again.
Child of Shadow (Shadow Hand 1, stance): If you move 10 feet or more, you gain concealment for a turn. No need to ever prepare blur again.
Mountain Hammer (Stone Dragon 2): Make a single attack, which deals +2d6 damage and ignores DR and hardness. For breaking objects, dungeon bypasses, and emergency digging - you can punch a hole in literally anything.
Crushing Weight of the Mountain (Stone Dragon 3): In grapples, you can constrict for 2d6 + 1½ Str with each successful grapple check. That can be solid damage if you're planning to put the squeeze on someone anyway.
Hunter's Sense (Tiger Claw 1, stance): Gain the Scent special ability. Allows you to find hidden (or even invisible) foes as well as track, if you've got the skill points.
Bolstering Voice (White Raven 1, stance): Allies within 60 feet (including you) get +2 to Will saves and a +4 bonus against fear effects.
Leading the Charge (White Raven 1, stance): Allies within 60 feet get a bonus to damage rolls on charges equal to your initiator level. Combines delightfully with pounce.
White Raven Tactics (White Raven 3): The other of The Big Ones. Long story short, it gives one of your allies another turn. Bestow it on your familiar to have it give you an extra turn every fight, and you'll wonder why you ever bothered with Quicken Spell.
Character creation is a tricky, exacting, and ongoing process. Each level gained brings the renewed agony of trying to make the best choices - fretting whether you picked the best feats, the best skills, the best spells, and eternally lamenting the abstract abyss that is opportunity cost. That said, heroics lets you do a little character building along the way, testing out (or even full-on adopting, if you're willing to sacrifice the spell slots) more feats without being locked into your choice or having to wait until the next level divisible by three. The popularity of flaws shows just how valuable an extra feat can be, and a low-level spell every now and then is well worth the power of having the right fighting style or defense on demand.