I don't know about the other Norse religions, but you don't have to play your character as a Viking to be a member of The Way of the Hammer. My character on Atamara (who's been in Eston, Coria, Caergoth, and Suville) has never been played as a Viking but still follows the Hammer. He also thinks that the Vikings of Maker are sub-human filth. In fact, I'd be hard pressed to think of anyone I've seen writing within the Hammer channel who plays a blood and guts, flea-infested, Viking barbarian.
In terms of Gods to worship, there's a considerable amount of potential there because you have an extensive pantheon of gods to choose from if you're looking for a patron god, or worship them all, or the all-father Odin. There's a ton of RP potential there.
The downside is that it's suffering from a major shortage of priests, which very nearly led to its collapse. It could also use stronger RP within it to make it more substantial.