Let the right one in really isn't a horror film. It's more about unlikely friendship and isolation through loneliness than it is a horror movie. That and it's a vampire flick, but it's a great film nonetheless and if you haven't seen it I totally recommend it. It's a foreign movie if you can put up with subtitles. Some horror recommendations. Splice - not really a great movie but pretty much has everything most horror fans appreciate. Funny Games - More of a psychological horror film. Ju-on - The japanese original of the movie "The Grudge" much more scary and less campy than the American version. Dark Water - There is an American version of this film but it's Japanese counterpart is much much more scary. The Host - A creature feature film from Korea that is part monster movie, part political satire movie, and part dysfunctional family movie. It's more entertaining than scary but I definitely recommend it. Other than that, I really can't say. The horror genre is my least favorite types of movies. Only because they are done with minimal amount of cost, shoddy/hammy/campy acting, and uninspired plot/story.
Frailty Audition Henry: Portrait of a serial killer Those are some "fairly non mainstream" movies I can think of
