As we develop new tools for the iPad to teach harmony and composition, we have found some cool articles, videos and other materials on something called the geometry of music. A little heavy going in some ways, but this is actually part of the "design" of the twelve tone chromatic system and equal temperment since the times of Bach. This "geometry" is simpler and more useful to understand than a lot of traditional music theory. Enjoy.
http://www.harmonisphere.com/SacredGeometryOfMusic.htm
A deeper less visual view of the geometry of music including some on rhythm is here.
http://soundmath.blogspot.com/2010/05/geometry-in-music.html
