This morning on  a Flowing Data blog post, I found this video:
Baroque.me: J.S. Bach - Cello Suite No. 1 - Prelude from Alexander Chen on Vimeo.
Baroque.me (2011) by Alexander Chen. Video capture. http://www.baroque.me visualizes the first Prelude from Bach's Cello Suites. Using the math behind string length and pitch, it came from a simple idea: what if all the notes were drawn as strings? Instead of a stream of classical notation on a page, this interactive project highlights the music's underlying structure and subtle shifts.

Grab and interact: http://www.baroque.me
More details at: http://blog.chenalexander.com/2011/baroque-bach-cello/

Built in: HTML5 Canvas, Javascript, SoundManager
Made while a resident at Eyebeam (http://eyebeam.org)


Of course, I clicked through to http://www.baroque.me  to see what "interact" means here.  As the page loads, it looks just like the video.  But if you grab one of the little white dots with your mouse you can drag it around, ruin the beautiful circle patterns the white dots are making, and totally mess up Bach's music.

Give it a try!