David Kaplan gave a good lecture that was based around magic, juggling and general performance skills, Possibly one of the most useful things I took from the lecture was the system that David uses for cueing and controlling his stage music, pure genius.

It involves a switch worked by magnets in his shoe, allowing him to stop, cue, and restart music by merely bringing his feet together. If you are looking for this device it was produced by wirelesswizardy (now creative entertainment solutions)