There’s a slew of great USB motion controllers now on the market you can buy but for those of you hackers and DIYers who enjoy the challenge of making one, go ahead and refer to this site on how to make your own DIY USB motion controller. (Of course, don’t forget we made one couple years back before the days of Wii)
This is the schematics for a PIC USB gamepad that I have built in a steering wheel shell. The code for the firmware was written in PicBasic Pro and it implements a HID USB device with 2 axes and 4 buttons (only 2 buttons connected in the prototype). The device is detected by Windows XP/Vista as a standard USB gamepad and can be used with many games and applications.