Eigenradio - Analyzes radio stations to produce statistically optimal music.
midisong.com - Interactive MIDI music composition site.
Pi Project, The - List members compose musical pieces that use the number/concept in some direct way. All tracks are 3.14 minutes and use pi as a formula in their title.
WOW/EM: Algorithmic Composition - Includes an introduction to algorithmic composition with an etymology and a detailed definition.
