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...
Low-Cost Multi-touch Whiteboard using the Wiimote
How the Wii Remote Works
eBay fake Wiimote review and testing
Wiimote Whiteboard vs. Commercial Electronic Boards
Raspberry Pi - How to use a Wiimote!
Johnny Lee: Wii Remote hacks
Cheap Wiimote Tabletop Touch Screen Display
Read more about The Geek Mind.