Beat Blocks is a tangible interface for a rhythm sequencer. The user is able to create and manipulate a 4-track drum loop by physically re-arranging wooden blocks within a 4x4 grid.
More at www.beatblocks.com
Audio d-touch is a collection of applications for real-time musical composition and performance, with very special user interfaces. The collection includes a drum machine and a sampling sequencer, both are controlled by spatially arranging physical objects on an interactive table surface. More info and installers at: http://d-touch.org/audio
Percussa AudioCubes are a platform for audio-visual creation and exploration. each containing its own self-powered wireless computer system. More info is available at http://www.percussa.com/