Matthias Wandel's rubber-band-powered Jenga Pistol brings an entirely new, nerdy delight to the staid old game of Jenga by using the rapid transfer of kinetic force to achieve seemingly impossible Jenga moves. He'll tell you how to make one (he also sells 'em).
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.