These make the Wii balance board look downright boring. Er, more boring.
There was a wonderful spread of strange and interesting indie games at GDC, including a special exhibit called Alt.Ctrl, focusing on projects that made use of unusual controllers. Bill Zoeker screwed around with these for a bit before discussing what it's like to play a game with pedals, knobs, dials, cables, sleeping bags, and a receipt printer.
If you want to find out more, I dug up the websites for all of these games: