Combat Expertise (3.5)

COMBAT EXPERTISE [General]
Prerequisite: Base attack bonus +1.

Benefit: You may accept a penalty to all your attack rolls up to a maximum equal to your base attack bonus and in exchange add the same number as a dodge bonus to your AC against the targets of your attacks. These penalties stay in place until the start of your next turn.

Comments
Combat Expertise is similar to Power Attack, but sucks more and has a ridiculous prerequisite. Instead, this version functions much more in line with Power Attack.