This video, via Uriel Yehezkel, demonstrates using the Leap Motion controller & GECO MIDI to control Ableton Live with hand gestures.
Here’s what Yehezkel has to say about it:
I took a little test on the LeapMotion controller with Geco Midi App and Ableton Live.
Because I come from a background of electronic music production and live performances techniques, this experience was amazing…. 
This way you can control more than 10 parameters simultaneously with both hands and take full control over the construction of the song, emotion and energy.
definitely think there is a future development and creativity with this technology.
In 2 words….. Crazy Shit,
Check it out and let us know what you think of gestural control of Ableton Live!
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Nice :)! Must be a whole new feeling to be a “dancer” that directly influences the music – and not just reacts to it.