6. Flight Of The Conchords (2007-2009)
The TV Show: The Emmy-nominated comedy series about Jemaine and Bret, two musicians from New Zealand looking for fame and fortune after a move to New York City, aired on HBO for two seasons. The show was loved by viewers and warmly received by critics (especially Season 2), but the show's stars decided not to come back for a third go-round, citing the time-consuming nature of writing and their wish to work on other projects.
The Film: As recently as 2011, Bret McKenzie said that he would like to make a movie if he could find the right story. With some dough and fan support from Kickstarter, though, I think both Bret and Jemaine might make the time and find the inspiration for a great musical flick that would go down as a cult classic for ages.