Well, if your looking for new artists with the same sound you might want to check out music map. http://www.music-map.com This site is very cool. All you do is type the an artist in, and the search results spin-off in groups and artist similar to the one you searched for. Pretty neat, huh?
Another way to find similar music and artist is Amazon. Search for an artist, and when you click the info, it will bring up a bar on the page saying, "Similar Interests". This shows different bands, artist and musicians that have similar sounds.
Tastekid is also a really neat site for finding bands and artist similar to your taste. Again, all you have to do is type in your preferred group, band or artist and it will give you all that match. It also has a "Give it a try" button to preview it. Sweet!