I enjoyed Jason Moore's presentation, Physical Interfaces for Musical Performance, at the O'Reilly Mac OS X Conference. He talked about several techniques for controlling a Mac during live performances, and even demonstrated of a nifty hand-built controller stuffed into a small toy electric guitar. Too bad he had to leave his gas mask-based controller at home; a wise move given airport security scrutiny.
My primary interest in this area is for the control of soundtracks during conjuring performances, but the geek in me loves the frankenstein-esque nature of it all. To that end, Jason's talk led me to some URLs that I definitely want to explore further: Chips International, i-Cube, and Making Things.