Using a nintendo wiimote and a projector you can turn any surface into an interactive musical dj tool.  This video demonstrates djay 2.0 on a macbook pro, projected unto a glass table. 

I used an IR light source strapped to my finger with a push button switch to activate mouse clicks. The  wiimote can track the position of my finger using Johnny Lee’s famous wiimote software (http://www.cs.cmu.edu/~johnny/projects/wii/). 

A mac version of this tool, which i used in this demo, “WiimoteWhiteboard” was released few weeks ago by and can be downloaded at :

http://www.uweschmidt.org/wiimote-whiteboard

the videos below are some first time users playing with the setup today: