With a wave of a hand or lift of a finger, you’re about to use your computer in a whole new way. The Leap Motion Controller senses how you move your hands the way you naturally move them. — Leap Motion, Inc
The App Store for the Leap Motion device is available since the 22nd of July and it is called [Airspace]. It has gesture control apps and different plugins that extend the functionality of existing software with new gestures and interactions.
You can get one for $79.99 and access the developer program to start playing with their SDK.