The Leap is a new motion controller that tracks the movements of your hands and fingers to a super-fine degree of accuracy. It takes the form of a USB dongle that sits in front of your keyboard, looking up at your hands and doing techno-magic to pinpoint their position in 3D space.
CVG have highlighted a trailer showing the tech in action, and it's pretty impressive. It shows a number of quick demo clips including one that involves playing Angry Birds with a pair of chopsticks, and another showing the player taking out some Combine soldiers in Half-Life 2 with a finger gun. On the Leap site its creators claim that it'll be "more accurate than a mouse, as reliable as a keyboard and more sensitive than a touchscreen." Watch and judge for yourself with this video.