This handy gentleman has built an (arguably ill-conceived, but nevertheless impressive) rifle-cum-slingshot that fires machetes, should you find yourself with the need to fire machetes. He also has a sideline in selling parts for making your own insane slingshot-like inventions.
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.