How do I make a game controller an active input device on my Mac-mini?
If you have a Playstation 3 controller, your Mac can recognize it as a bluetooth device and if you pair it with your computer you can set it up to be used as a game controller for your Mac.

I have only tried it with SNES9x, and it DOES work with that app. Playing Super Street Fighter with a wireless PS3 remote is pretty bad ass, I must say, haha. 

Not sure what else it would work with, but I am sure you could map the buttons and set it up to work with other games and services once you pair it.

Good luck!