Wiimote Projector Whiteboard - Wii Hacks
Using infrared (IR) light pens and the Wii Remote, it is possible to create very low-cost multi-point interactive whiteboards and multi-point tablet displays.
The Wiimote interactive whiteboard. Commercial versions of these things are expensive and heavy. His technique doesn't even need a projector, just a computer, a Wiimote and a simple IR emitting pen. The pen is just a stylus with an infrared LED in the tip. Hit the video after the break, and you can grab the software from his site
here.
http://www.youtube.com/watch?v=5s5EvhHy7eQ