Michael Dougherty's Trick 'r Treat has built up a cult fanbase since it was first screened at Butt-Numb-a-Thon in 2007.  From there, it went through multiple festivals including Fangoria Convention, Fantasia Film Festival, and Fantastic Fest.  The movie finally received a limited release in 2009, and the cult has continued to grow.  For those unfamiliar with the film, it's an anthology of loosely-related Halloween stories that all have a darkly comic twist.  The cult following has kept the surprises secret, and while I don't personally find the movie scary, I thought it was quite clever.