One of the odder little bits of a typical Google results page has to be the "Similar pages" link for every hit. Clicking on it generates a list of other sites which usually (but not always) have thematic connections to the original. The Similar pages link for WorldChanging.com, for example, quite reasonably points to Viridian Design and Weblogsky (our own Jon Lebkowksy's personal blog), but also to the Amazon link for Nick Hornsby's book High Fidelity. Huh?
Still, exploring the corridors of iterated similarity you get on Google is a good way to spend an afternoon. That's what makes the TouchGraph Google Browser so much fun. Entering a URL lets you see a graphical map of its various "Similar pages" links, as well as the pages similar to those pages, and so forth. It's Java-based, so it presumably runs on anything able to run JRE 1.3+, with typical Java alacrity.
Once you have your initial map, you can then start building out the maps of similar sites, even adding seemingly-disparate links until you find connections. Surprises are common. TGGB is an amusing way to spend the day, yes, but also a useful tool for seeing links that you may otherwise miss.