My concept is Encouraging new music discovery through hand shadows. In a nutshell: user makes hand shadow; it’s detected by an infrared motion sensor + video cam tucked away in a lamp then wirelessly sent to a LastFM/Pandora-like app that interprets the shadows to intelligently determine the song to play.
I choose hand shadows because human hands are highly expressive, and creating shadows with one’s hands adds an element of playfulness.
It feels natural to show like/dislike of a song through thumbs up/down or to control volume by holding up fingers; but the real fun is to imagine hand shadows for particular genres or bands.