There have been some truly awful movies listed. I hate to be a movie snob, but if you think The Ring is scary or "horror", you either have a vagina, or you have little to compare it to.

Maniac is great. Spinell is fuckin' freaky. The subway bathroom scene alone should be studied by the current crop of tardball horror/music video directors. Less is always more from a photographic standpoint in slasher films.

Frailty is great too, but I don't consider it horror at all. Paxton nailed his directorial debut. I'm actually fond of the Dawn of the Dead remake as well, though it's not nearly as good as the original.

I've recommended Living Hell to a few friends and each said they liked it and that it creeped them out. Definetly worth a rent if you can find it. Here's a trailer. (It's also linked on the IMDB page.)