The Shape of Song
The Shape of Song is a Java applet that analyzes and visualizes MIDI files:
The diagrams in The Shape of Song display musical form as a sequence of translucent arches. Each arch connects two repeated, identical passages of a composition. By using repeated passages as signposts, the diagram illustrates the deep structure of the composition.
Pretty cool. I think the server's pretty stressed out right now though, it's going very slowly.