At Moog they know how to play in mid air with synthesizers! Look at this amazing ‘Theremin’ (invented in about 1954!) which let you play a synth without touching any keys!! Check it immediately from 2:55 – 6:02 mins:

The Moog Music story began around 1954, when mister Bob Moog started to build theremins, one of the oldest electronic instruments, and the only one known that you play without touching, in his basement together with his dad. For who doesn’t know, a theremin is a single oscillator instrument that uses two metal antennas to control both pitch and the amplitude.

Read more about the theramin on the Moog site here