I got turned on to this little list today, courtesy of an email tipster (thanks, Jennifer!), which chronicles some of the worlds more bizarre (at least from the eyes of it’s author) music genres. Of particular interest is their inclusion of Nintendocore (which is more of a Frankensteinian abortion than a genre, but whatevs), Pornogrind, Pirate, and Viking Metals. They use Amon Amarth as an example of the last one there -- which isn’t exactly accurate -- but it’s a good list notwithstanding.
Check out what other genres made their way on to the list and whatever you do, do not pass up Mongolian Throat Singing. That is some ‘strange world’ stuff right there.