Recently I have acquired two Kommander`s from Koma Elektronic.
The Kommander`s provide the Serge modular synth with gate and CV signals by tracking my hand movements.
This is very similar to the possibilities of the Theremin , vimeo.com/42150452 , but in a much smaller package.
On the other hand Theremin is a self contained instrument and Kommander is not.
More info on the Kommander can be found at Koma`s page koma-elektronik.com.