The Media Computing Group : Multi-Touch Framework
MultiTouch.framework is a native Cocoa multi-touch framework for Mac OS X. It uses the default event handling system and the responder chain of the operating system, providing a familiar application programming interface to Mac OS X developers.
Johnny Chung Lee - Projects - Wii
Since the Wiimote can track sources of infrared (IR) light, you can track pens that have an IR led in the tip. By pointing a wiimote at a projection screen or LCD display, you can create very low-cost interactive whiteboards or tablet displays.