Wii!
If you want to use your Nintendo Wii remote (Wiimote) with your Mac (via Bluetooth) (perhaps because you liked Tony Stark’s movie UI and a Wii is a cheaper way to get accelerometer gear 
check out
- DarwiinRemote
- The Wiinstrument for use with MIDI and/or Garageband.
- Remote Buddy
For the more programmatically inclined there’s
- WiiremoteJ
- Wiimote Simple (an open source Java library)
- WiiJuce
