Well, contrary to Rebecca's fears, the ULC doesn't actually require that you believe anythig that they say. They're very Universalist in that aspect. Yes, the guy who founded the Church was "Christian", but his prime tenant was that everyone had a right to worship the devine in their own way...even if it's not worshiping a devine at all.
Both Mama Mortis and I are ordained Ministers through the ULC. I even have the snazzy little "Clergy" card. I've personally performed three weddings (all in Illinois where an ordination is required for religious ceremonies) and I've never had an issue with it. One of the times, the Bride's Mother gave me the confuzed puppydog look when she asked me what religion I was and I replied "Agnostic". She desperatly wanted to ask how an Agnostic could get ordained, but thought better of it.
IIRC, MA requires a letter to the Sec of State stating your intention to perform weddings.
Dunstan, I'd suggest ULC.