VERY cool project out of MIT Media Lab. It's called the Audiopad. I'm not even totally sure how to describe it. It's a surface with some kind of display built in that lets you play sounds, but it's a bit more complex than that. From the web page:
It is a composition and performance instrument for electronic music which tracks the positions of objects on a tabletop surface and converts their motion into music. One can pull sounds from a giant set of samples, juxtapose archived recordings against warm synthetic melodies, cut between drum loops to create new beats, and apply digital processing all at the same time on the same table. Audiopad not only allows for spontaneous reinterpretation of musical compositions, but also creates a visual and tactile dialogue between itself, the performer, and the audience. [Audiopad]
The page has a six minute video (available in Quicktime or Windows Media) that shows it in action. It is seriously cool. I'd love to get a chance to play with it sometime. I wonder if these guys could come out and open up some Wednesday night.