A company called Cam-Trax is developing software that allows almost any object to be used as an input device for a PC. Using a standard webcam, the software can be configured to recognise an object, track its movements and feed the input into a game or application. See it work in their demo video. They claim to be nearly ready to release a beta version but I suspect they're being optimistic. Watching the bouncing ball demo reminded me of the EyeToy for PlayStation which was... well, not very good. But the way this tracks the contours of objects rather than human hands makes me think it will be much more reliable. The stuff you can do with a Wii remote is pretty cool but how much cooler would it be to use anything as an input?