Have you been there before? I've been there twice. If you haven't been, you are in for a wonderful experience. Iceland's beauty is incredible.

Sorry I can't tell you about any trad, though. Have you checked with the Iceland Tourist Board? I've found them helpful. Under "Tours and Activities" they have boxes in which to search for concerts and culture.

Another thing to do is to ask at the lodging where you are staying. Hotel (etc) managers often have local knowledge.