Here’s a cool DIY on how to make a USB device with a PIC via 
.
They also have a simple howto on making a USB thermometer to get you started right.
The code looks pretty simple for anyone with prior PIC experience.
You could probably use this for making your own wii controller device for PC.
Other interesting stuff at Zedomax.com: Circuits, DIY, DoItYourself!, Hack, how-to-make-usb, make, makezine, microchip, Microcontroller, Misc, PIC, usb-hack, usb-hacked, usb-hacking, Zedomax