Tuneglue
TuneGlue is a service that's powered by Last.fm's discovery engine. It has a surprisingly deep catalog of artists, their discographies, and their relationships to one another. Type an artist or band name into the search bar and click the magnifying glass to bring up that artist's name. If you click on the name, a menu appears to either expand (which means display other artists similar to the one you typed in), list releases from that artist (which opens a window with the artist's discography and albums listed), lock its position in the diagram, or delete it from the list entirely.
