Ever since seeing an advert for a ( monophonic ) Analogue to Midi converter , I have been imagining possible uses of a midi controller that takes its input from where you move your hands in space .
We already have ribbon controllers and photo-sensitive controllers such as the Beamz laser thing , but with a proximity-sensitive arrangement such as a theremin hooked up to an analogue/midi convertor there would be a greater range of commands possible .
Transport control from an unlit vocal booth by making gestures in the air !
I expect someone will reply now to say that they have adapted a wifi game controller to send midi info and they already set project tempo by stomping and control a wah effect by moving their foot in the air .
Slightly off-my-own-topic now , my Imagination-Of-The-Future just ran riot at the implications of this video ; http://www.synthtopia.com/content/2011/07/08/music-robot-plays-the-theremin-follows-the-guitar/
Will we be setting tempos by strumming air guitars next ?