In Dungeons & Dragons' third edition Player's Handbook, Ambidexterity is described as a feat (special ability) that your player character (or "PC") can acquire. From the Player's Handbook (p.80):

"You are equally adept at using either hand.

A great feat if you have plenty to spare, in this noder's opinion. It helps reduce penalties for being a badass and fighting with two weapons, which, obviously, is for hardcore ass-kickers. Similarly, it helps the user use double weapons.