I also really like last.fm's "neighborhood" feature. It can show you people who's likes are alot like yours. Listening to their lists as a radio station is great for discovering new gems. Sometimes I listen to people who are 95% match (not very many of those for me). But sometimes I prefer 80% or 75% just to hear more new stuff.
By the way Im gp1628 on last.fm but I will warn you that very few people can stand my "radio station". Its way too spread out. Everything from great gandma to grandkids, all genres, many countries, etc. Some people like to collect some of my stranger playlists (oddball waltzs, goth, pagan, geek, acappella, parody, cover, and of course the ever popular WTF) but when its all together its apparently hard for anyone to take.
Thats the story of my life, jack-of-all-trades in more things than just work history.
Tip:
If you use iTunes the best tip Ive ever gotten was from LifeHacker.com about using comment tags to automatically fill in many different playlists. When I download a new song I add tags to the comments field of it. Things like chores, relax, workout, dreams, names of people who might appreciate it most. Then I have "smartlists" in iTunes that build off of a certain word being in the comment field. That way adding one song can automatically add it to multiple playlists.