The leap motion controller lets you track your hands and fingers very much like Microsoft’s Kinect lets you track the whole body. This lets you create in-air gesture interfaces for e.g. controlling a robot hand (remote surgery), play games (shoot guns, fly planes) or musical instruments (pull strings).
However, when the leap motion device was released in 2013 it was quite a disappointment. The sensor plus software often loses track of individual fingers, usually when the hand is rotated (even by a small angle). This greatly limited its practical use in applications. It has never been clear whether this has been a software problem or a limitation of the hardware.
Now leap motion has released a new software which seems to indicate that this was a software problem. Even better: it has been fixed in the new v2 release. Look at this video. By the way, I’ve given it a try myself and the signals seem to be much, much more stable.
For downloading the beta version of the new software, go here: https://developer.leapmotion.com