There are a couple feats that stood out to me in Complete Mage as being extremely powerful -- one for wizards and one for sorcerers.
Wizards get Alacritous Cogitation. Once/day, you can spontaneously cast any spell you know from an open (unprepared) spell slot. The feat also has the poor wording that "Casting the spell requires a full-round action." I'm sure that will be be ruled to add something like "or the spell's normal casting time, whichever is longer."
Sorcerers get Rapid Metamagic. It requires 12 ranks in Spellcraft (so it's not available until 9th level), but it completely removes the increase in casting time for spontaneous metamagic.
A couple other items of note: Abjurant Champion is a full-BAB, full-casting-progression, d10 HD prestige class with some nice class abilities. Prerequisites aren't too bad: BAB +5, combat casting, proficiency with one martial weapon. The BAB requirement probably makes it a second prestige class rather than a first, though.
There's also a sorcerer variant that could work well with it. You lose one spell known, but you get +2hp per sorcerer level and martial weapon proficiency plus weapon focus with a melee weapon of your choice.
Wizards get Alacritous Cogitation. Once/day, you can spontaneously cast any spell you know from an open (unprepared) spell slot. The feat also has the poor wording that "Casting the spell requires a full-round action." I'm sure that will be be ruled to add something like "or the spell's normal casting time, whichever is longer."
Sorcerers get Rapid Metamagic. It requires 12 ranks in Spellcraft (so it's not available until 9th level), but it completely removes the increase in casting time for spontaneous metamagic.
A couple other items of note: Abjurant Champion is a full-BAB, full-casting-progression, d10 HD prestige class with some nice class abilities. Prerequisites aren't too bad: BAB +5, combat casting, proficiency with one martial weapon. The BAB requirement probably makes it a second prestige class rather than a first, though.
There's also a sorcerer variant that could work well with it. You lose one spell known, but you get +2hp per sorcerer level and martial weapon proficiency plus weapon focus with a melee weapon of your choice.