Echotron is a WebGL demo created by Alex Wayne which serves as a music visualizer for files produced by echonest.com. Unlike traditional WebGL visualizers which “visualize the waveform of the music, analyzing it in realtime, and animating some state based on that feedback”, Echotron differs because it uses echonest info, which “can make the visualization respond to semantic music events. When a beat happens, we can make the visualization pulse or jump.”
At the moment there is only one sample song, but I’m hoping to see more soon. Those interesting in adapting the code can check out the github page but I also recommend checking out Alex Wayne’s detailed write up.