On cre.ations.net, there is a short video of a simple strobe-light-enhanced fountain, the Time Fountain. A fellow has added timed, strobing LEDs to a simple water stream to make art. The video posted on this page is neat.
A commenter on MetaChat, where I found a link to this site, tells us that this effect as a lot to do with the extended Euclidean Algorithm. I'll take his/her word on that. The EEA is beyond my ken, but the water drops sure are pretty.