Etsy seller boonerings has a $385 titanium "utility ring" with five in-built tools: "a working bottle opener, a straight blade perfect for cutting packing tape or fishing line, a serrated blade for tougher things like nylon strapping or those tough to open electronics heat sealed packages, a saw for cutting plastic and wood, and it has a comb" (the comb is recommended primarily for mustaches.
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.