Brutal Throw, in Complete Adventurer.
Alternatively, Bloodstorm Blade in Tome of Battle at level 2 gets the ability to treat thrown weapon attacks for the round as melee attacks. Among other things, that means you can apply str to attack with them. Activating is a swift action, but otherwise can be used as often as you like.
Bloodstorm Blade is a pretty awesome class for thrown weapon characters in general.