If Celtic music with some punk (uh, lots of punk) influence sounds appealing to you -- kind of the Clash meets the Pogues meets the Chieftains -- try Dropkick Murphys. They're not exactly "new" artists, since they have 5-6 CDs, but they're not well known yet outside their mainstay Boston-area and Irish diaspora audiences.

I recommend the "Blackout" CD. The two full downloads available from the "Blackout" page on their Website are great examples of their stuff.

"These go to eleven."