Pandora: the Music Matching Service
Pandora is a great service if you know which music you like and want to discover something similar.
Pandora is a music discovery service designed to help you find and enjoy music that you'll love. It's powered by the Music Genome Project, the most comprehensive analysis of music ever undertaken. Just tell us one of your favorite songs or artists and we'll launch a streaming station to explore that part of the music universe.
We take your input (artists, songs) and feedback ("I like this", "I don't like this") and use the Music Genome Project to create stations that play songs that are musically similar to what you've told us. That's it; only the music counts. We don't care how popular the artist is, who's backing them, and we don't care which genre bin they usually belong in. Only the music matters.
Pandora is available in a free ad supported version as well as a subscription based versions. The library is huge; ~400.000 songs from more than 20.000 artists. You can buy the songs you discover, if you wish, thanks to the partnership with Amazon and iTunes.
I threw some famous as well as unknown artists at it and I have spent the evening listening to lots of great music.
Thanks for the tip Paolo!