For the final portion of my undergraduate degree, I built a multi-touch table, and created software for it.  It used frustrated total internal reflection to illuminate fingers on the surface of the acrylic and a modified web-cam for an Xbox 360 to detect them.  Unfortunately, due to time constrains, a majority of this project went undocumented.

The man in the photos is my father, who helped with constructions based on my design.

The table had two positions.  The first position (seen above) was laying flat, for a seated interface (the projector was placed under the table). The second position (seen below) was angled for a more comfortable standing experience.