Plink: Collaborative Music With Chrome
The notes are fixed, but there’s a lot of fun to be had with timing and simply messing around (it’s hard to make anything that sounds bad).
Fun stuff (via MetaFilter
In Bb 2.0: Collaborative Music Project With YouTube Videos In Same Key
Auditorium: Relaxing Flash Game Involving Space And Sound
Turn That TENORI-ON!
Sinuous: Soothing HTML5 Game
Conductor: Musical New York Subway Map