Tattiebogle.net - Mac OS X driver
http://tattiebogle.net/index.php/ProjectRoot/Xbox360Controller/OsxDriver
"have created a USB driver which allows you to use wired XBox 360 Controllers via USB, and wireless XBox 360 Controllers via the Microsoft Wireless Gaming Receiver for Windows, on your OSX machine, including support for the Apple Force Feedback library. The driver is licenced under the GPL."
Play Rhythm Games using any MIDI Instrument
http://egyokeo.com/midihero
"wouldn't it be great to be able to play Guitar Hero on the drums?"
Create Digital Music ยป Gorgeous DIY MIDIBox64, MIDI Controller for Live, Traktor, Max
http://createdigitalmusic.com/2008/05/13/gorgeous-diy-midibox64-midi-controller-for-live-traktor-max
"It consists of 16 knobs, 5 faders, 16 arcade buttons, and 32 MIDI controlled LED buttons. "