Apparently there isn't much money in documentary films these days -- except when they are about serial killers. "America as a whole is utterly fascinated with serial killers," says Julian P. Hobbs, director of Collectors, a documentary film about two guys obsessed with serial killers. Read more here.That understanding of the market demand is partly what's driving all the film attention being given to serial killer Aileen Wuornos. A newly-released Hollywood film "Monster" starring Charlize Theron, as well as two documentaries are based on Wuornos' life. Listen to the audio report on NPR here.Small, independent, documentary film makers have found what seems to be one area where they can make money: following the lives of serial killers (and even their groupies).