Wiimotes as multitouch whiteboard sensors

Johnny Lee's description of "Low-Cost Multi-point Interactive Whiteboards Using the Wiimote" may sound boring, but it's actually a very cool and very innovative use of the Wiimote. Since you can hook the controller up to your computer and accept inputs using the Wiimote library interface, you can use its infrared sensors to detect and track infrared light on any kind of surface.