TrackMate

TrackMate is an easy-to-build tangible user interface. If you want to link physical object directly to digital information, TrackMate is an open source initiative to create an inexpensive, do-it-yourself tangible tracking system. The Trackmate Tracker allows any computer to recognize tagged objects and their corresponding position, rotation, and color information when placed on a surface. Trackmate sends all object data via LusidOSC (a protocol layer for unique spatial input devices), allowing any LusidOSC-based application to work with the system.
Check their website to download Trackmate & LusidOSC.