Cool work! Can you comment more on the different sparse matrices you're using along the left-hand side? You said they are sparse matrices of University of Florida... are they just provided by the University or are they of some significance?

Also: I don't know if it's a bug, or what, but many of the graphs appear to have some outlying points that don't seem to be connected to anything: http://i.imgur.com/qXNjO.jpg

I'm viewing it in Windows 7 on Chrome 18.0.1025.168.