While I was listening to my Thumbprint radio station today Fozzy came on the radio. They seem to be viewed as a bit of joke (name, Chris Jericho as a singer), but I like a number of their songs. Those dudes can all play, Jericho has a really good voice, and they put on a great live show. I think more hard rock fans would dig them, if they gave them a chance.
Frank Turner is another one that I think is underrated (At least here in America). That dude writes amazing songs, and I've never quite pieced together why he isn't more popular.
What bands do you think are underrated?
Moderator Edit: Removed links to non-Pandora music/video content