^Blalock has a pretty sweet torrent going monthly; also, probably irrelevent for the american audience, but Triple J Unearthed (not sure of the exact link) has a lot of unsigned artists. Takes a bit of digging, but there be gold to find.
I like Pitchfork, but never go buy something just because Pitchfork likes it, sometimes it's complete shit or something you're not into at all. I like to check what Pitchfork rates albums though, usually they get it right. The best indie sources though are when you go out and discover a band on your own, whether its an opener for a band you're seeing or something you hear on the radio, it's always the most rewarding to go find a band on your own.