I just stumbled upon a cool feature of Yahoo! Unlimited (Yahoo!’s new subscription music service). It’s a feature that creates a playlist of music similar to the artist or song you are browsing — for some reason the feature isn’t available in album view.
For example, if you were browsing the artist page for Rush (for some unknown reason), there is a button called Create a Playlist of Similar Artists as shown below:
If you push this button, the Yahoo! Music Engine (the Yahoo! Unlimited client application) automagically creates a playlist of songs similar to Rush’s music. Here’s a view of the newly created Like Rush playlist tacked onto the end of my playlists.
Browsing the playlist, you can see what kind of songs Yahoo! thinks are similar to Rush. Overall, I’d say that it’s pretty good at picking similar songs for the playlist (at least in this example).

I’ll be playing around with this feature more to see how it aids in discovering new music.
P.S. You should probably sign up soon for the full year of Yahoo! Unlimited while it’s still only $60/year. As quoted over on the O’Reilly Radar, Jerry Yang says that the pricing for Yahoo! Unlimited is an “introductory price.”