I used to get a big kick out of the Pandora algorithms, and how they picked "similar" music. My favorite approach was to seed the engine with a single song, and see where it went. I've been doing the same thing with the Grooveshark autoplay feature lately. Yesterday I seeded it with "If You Could Read My Mind" by Gordon Lightfoot, and got a very strange result. Grooveshark alternately played Beatles songs and country songs by the likes of Hank Williams, Willie Nelson and Waylon Jennings. I can understand the country connection, but I was expecting more of a folk selection. But a heavy dose of the Beatles? I didn't see that coming.