I used these when I performed electronic music. I hijacked the embedded sensor in each hand and routed it to a Max/MSP patch in order to trigger software events and/or MIDI messages. The next step will be to add wireless functionality so that I can throw these into the audience during performances. More detailed notes and images available here. This also got some considerable link love, a first for me.
PATCH - by UM Project
A micro-grid in which solar power is distributed and stored in discrete furniture modules throughout the space, each exhibiting its own unique behaviors.