My favorite are the Ayn Rand Objectivists. (Did anyone catch the Showtime original movie the other night?) After college, circa '92, I was kicking it in Austin, Texas and joined the International Socialists local, partly to discuss Marx, partly as an amateur anthropologist studying the tribe. I witnessed a great debate between an ISO heavy and an Objectivist heavy - the large crowd of spectators was half and half. There was much heckling.
The ISO teamed up with the local Anarchist group to lead some great protests against the privatization of the U. of Texas student union food services. The strategy meetings were pretty tense, though.
Peter "I wouldn't want to join any group that would want me" Kilander
PS - Max, what about the South African Communists who helped throw off apartheid? Anyone?