Well, Norway wasn't really serfdom (serfdom basically evolved from Roman slavery). It was rather a matter where free farmer districts endorsing one king or another. Keep in mind that the troop levies were locally managed but not on the continental feudal model, and these local assemblies were the primary legal bodies of their areas. I don't think it was any less democratic than the US today.

Additionally keep in mind that during much of the time, if there was a dispute (and this was common before the Conversion), these districts could and did lead to the rise and fall of kings.

But even if you say monarchies are out (in which case the UK today is not democratic), you still have Iceland, Gottland, and much more.