What are some good doentaries about weird subcultures?

I've noticed my favorite movies all have similar structures. They take a weird subculture and tell the story of a few people in that subculture. Usually, the story leads up to some event at the end. Wordplay - about competitive crossword puzzle players - is probably the best example. Spirit of the Marathon, about marathon running obviously, was also great. I also really enjoyed "Young At Heart," about senior citizen singers. Does anyone else know about movies that fit into this category. I'm not so much into African children with cleft lips or attacks on the Bush administration. Im looking for lighter stuff.