360 Gamepad will work with OSX. You need the tattibogle (sp?) driver, and a little bit of patience. Having Gamepad Companion will also help with games that do not have automatic gamepad support.

I use it myself, and havent had any major problems. If you have a wired controller, and a version later than .8 it will crash the mac when you unplug the controller, wireless can be hooked up via the wireless reciever kit, and does not have this issue.