Here's an idea that my friends and I have tossed around.
When using a light weapon or a rapier, Dexterity is automatically the relevant statistic for to-hit, strength determines damage.
Weapon Finesse: As in PHB but can be applied to any medium weapon.
New Feat:
Precise Blows:
Prerequisite: Dex 12+, BAB +6, proficency with chosen weapon, must use Dexterity as relevant To-hit statistic.
Effect: You can add your dexterity bonus to your damage instead of your strength bonus.
Normal: You use add your strength bonus to your damage rolls.