"Audiopad 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. "
See website: http://www.jamespatten.com/audiopad/