James Halliburton was one of the (smart) entrepreneurs who turned down money from the Dragons' Den TV show. His invention, the Waterbuoy, is basically a keychain fills a strong balloon with a flashing light when submerged in water. The Waterbuoy can float items weighing just over 2Lbs. Very cool idea, not sure why but I really want one. Watch the video of the waterbuoy in action after the break.