Australian artist Andy Thomas recently built a visualizer for birdsongs, the latest in his fascinating line up of so-called "audio life forms." As the term implies, these gorgeous creations look like the sounds they represent and react accordingly. The end result is an acid trip of an experience.
In many ways, Thomas's visualizer is just a slightly fancier version of what you get with iTunes. It's also heavily inflected with his own creative energy. If you watch the video he made for a crow's song, you can see how the idea starts out with a drawing and then eventually morphs into a 3D animation.