This projects let's you use a Nintendo Nunchuk controller as an USB gamepad on your computer (a joystick, 2 buttons, and it also 3 axis of acceleration data). It also let's you use it as an USB mouse, but this function can be disabled by a jumper. Tilting the Nunchuk is the same as moving the mouse wheel.
Video, circuit, and code all here:
http://frank.circleofcurrent.com/content.php?page_id=nunchuk_joystick