Fifteen uncoupled simple pendulums of monotonically increasing lengths dance together to produce visual traveling waves, standing waves, beating, and (seemingly) random motion.

For more details see http://sciencedemonstrations.fas.harvard.edu/icb/icb.do?keyword=k16940&pa...

The period of one complete cycle of the dance is 60 seconds. The length of the longest pendulum has been adjusted so that it executes 51 oscillations in this 60 second period. The length of each successive shorter pendulum is carefully adjusted so that it executes one additional oscillation in this period. Thus, the 15th pendulum (shortest) undergoes 65 oscillations.

Our apparatus was built from a design published by Richard Berg [Am J Phys 59(2), 186-187 (1991)] at the University of Maryland.

From Vimeo...

Made with Processing (processing.org). Audio by Radiohead (Weird Fishes from In Rainbows).

Read about this project here:
flight404.com/blog/?p=121

Update-----------
Decided to go ahead and submit it in the Radiohead video contest thingy.
aniboom.com/Player.aspx?v=210097
Update-----------

There is also a higher res quicktime version (200MB) linked from my blog.

Many thanks to my fellow Barbarians
barbariangroup.com
and Mike Creighton
mikecreighton.com
for giving me great feedback as I was working on this.