I have to get myself one of these Air Guitars by Takaratomy. They have a Pro Electric version and an Acoustic one. Each Air Guitar consists of the upper neck of a guitar with infrared ray strings that make the sound as your fingers hit the fretboard. The controller has seven buttons on the front to press to hold down chords and also buttons on the side to identify the chords as major, minor, augmented or diminished. Video of the Air Guitar in action here and a demo here.