This is found music at it's best. I stumbled on to a new online flash music project called Muxicall.
Basically, it's an interactive music sound board that has the notes organized in a very interesting way. By clicking with your mouse, you make music.
In addition, it's also a shared music space, so that as other users login and play with it, you all make music together.
Check it out at: http://www.muxicall.com/