While not really spatial, I thought Music Plasma was an interesing application for graphically showing relationships for data points. In this case, they’re pulling data from Amazon’s databases to show how certain bands “relate” to other bands, at least as far as Amazon’s customer habits are concerned. It’s interesting to remember that relationships beyond spatial ones can be shown using some of the more abstract concepts we see everyday in maps. Plus you can find really cool music you never heard of by starting with your favorite bands. That’s always cool.