Camera Tracking

The TUIO Protocol

Color Tracking

Blob Tracking

Marker Tracking

Useful links

http://tuio.org/
Information about the TUIO protocol.

http://nuigroup.com/
A community based on the development of multitouch surfaces. The forum is a great source of information on everything related to finger tracking and DIY multitouch interfaces.

Software

http://ccv.nuigroup.com/
Community Core Vision (aka tBeta) is a blob tracker developed by the members of the NUI Group Community. Excellent for multitouch surfaces and other blob tracking applications. Sends tracking data via TUIO.