How about a set of electronic drum pads inserted into your pants and shirts? Drumming your fingers on your legs can turn into a snare roll; tapping your chest rhythmically can sound like a tom or a bass beat.
Drumpants doubled the ask on its Kickstarter campaign, which closed last week. The Arduino-driven sensors are programmed through an iPad app. They can be any kind of triggers, really; the video shows them answering an iPhone and driving a slide show. But the aim is making music, particularly percussion.
Sensor sets start at $99 and go higher as you add Bluetooth and more sensors. They ship in May to a busker near you.[youtube http://www.youtube.com/watch?v=6VS2jWqFKM0]