Check this out: Auditorium!

I was directed towards this little gem by the Penny-arcade guys, and I was immediately hooked. The music doesn't show its face until you start playing the game, but when it is heard, it is great. The objective is the manipulate the stream of light in a manner that directs itself towards the column of bars. Only then will the music appear, and it is quite satisfying when one completes a level. The beginning goes by pretty quickly, but it slows down when the levels get more complex with the different angles the light must make. Enough talking about it, play it now! Enjoy it for yourself.