Also, besides Pandora, there are a lot of music blogs that go pretty in depth to particular genres. I don't know your cup of tea for music, but two pretty good music blogs are Nine Bullets and Big Rock Candy Mountain.
But again blogs aren’t the same. That’s more of the tunnel vision, if you like genre X you might go read the blogs about it but you’re not going to go read a blog about a genre you don’t like or don’t know anything about. You could walk into a record store and hear anything, or be recommended anything. The web gives you what you’re looking for, the real world gives you what you didn’t even know existed.