The forthcoming iRing from IK Multimedia will let you control two of their music apps via hand gestures. But according to a report on CNET, they're encouraging developers to use this technology in games, health and fitness software, and other mobile apps. The iRing interacts with your FaceTime camera, and controls your device when you move your hand up and down, left and right, or twist it. The goal is to let musicians and Djs use IK Multimedia apps such as GrooveMaker and VocalLive to control music and sound effects without touching their device.
The device isn't yet available but is expected this quarter. It's available for preorder on the IK Multimedia website. The company also plans to release two free apps that will work with iRing: iRing FX/Controller and iRing Music Maker.
Their video demo gives you a good feel for how the iRing works: