Virtual Air Guitar:

Aspiring rock gods can at last create their own guitar solos - without ever having to pick up a real instrument, thanks to a group of Finnish computer science students.

The Virtual Air Guitar project, developed at the Helsinki University of Technology, adds genuine electric guitar sounds to the passionately played air guitar.

Using a computer to monitor the hand movements of a "player", the system adds riffs and licks to match frantic mid-air finger work. By responding instantly to a wide variety of gestures it promises to turn even the least musically gifted air guitarist to a virtual fret board virtuoso.

Here's the official website.