One of the ideas that’s been floating around my How-To bin for a couple of years is an under carpet zone switch dance pad. [sprite_tm] beat me to it in late 2006, and did it even better. He was using a QT160 chip – a nifty six channel capacitive touch sensor to make touch switches. Instead, he used an Atmel to duplicate the technology. He was able to place foil panels below his carpet. Step on one and it acts like you just closed a switch. The QT160 is now available, but the atmel he used is actually cheaper.