Matrix

This is a very cool design that I stumbled across a few months ago, not only is it design really well as a website, being aesthetically pleasing  but it offers such simplicity that people who have no understanding of musical theory can construct small sequences, yet is laid out in a manner that people who DO understand the theory can create chords and notes in a logical progression.
www.sembeo.com/media/Matrix.swf

Stuart Baynes