This isn't a specific station, but I use something called Last.fm.
You can listen by downloading a client, or through the website (the client is better). Last.fm lets you put in a keyword (tag, usually a very specific genre or category) or an artist name, and then in automatically generates a radio station track by track with music that either matches the tag, or that is similar to the artist. As you listen, you have the option to Love or Ban a track if you particularly like or dislike it. The program continues to generate the streaming radio, but keeps a record of what you Love and Ban in order to choose tracks that you are more likely to enjoy.
The program can also run alongside plugins to music players (Windows Media Player, iTunes, others). When the plugin is turned on, it uploads to a server a record of the songs you listen to, which also helps it choose music that you might like. This information is also used to generate charts of the worldwide popularity of albums and songs.
It's a great way to discover new artists that you'll enjoy.
The $3/month subscription gives you a faster connection to the website, and special stations such as "Recommended" or "Loved Tracks".
http://www.last.fm