Symphony is a useless little app that makes a lot of noise, Mardi Gras style. It abuses the secret ingredient API to determine when things happen on your computer — you start an application, move a window, type something. For each event, a sound is played. They all wash together and form a soundscape.
Since judging, I’ve fixed a few bugs, added a feature or two. Symphony now requires 10.3.9 with Quicktime 7 or Tiger. It is built universal.
[Update: Corrected link to source]