I spent a while on somebody else's blog entry recommending horror films and thought I should make my wisdom and experience available to the masses.  First, I promise on pain of death that you're not going to be Rick Rolled if you click on one of the youtube links below.

At the theater:  Although not as good as [REC] was, Quarantine was still a good October scary film.

On DvD:  The Descent was good.  Five attractive, plucky girls battling cannibalistic troglodytes with rock climbing hammers can't be all bad. http://www.youtube.com/watch?v=l5I1q4KhKNU

If you want extremely high quality campy film, Slither is one of the best over the top horror film I've seen in ages.  A classic one liner from Slither, "Somethin's wrong with me...."  Check out the trailer on youtube if you doubt the awesomeness that is Slither.  http://www.youtube.com/watch?v=T-qwPDPa3vk

Many people have limited experience in subtitled or foreign film.  I personally certify that the following are worth the trouble or inconvenience of reading subtitles or tolerating bad dubbing.  The French flim Inside (À l'intérieur) was one of the most graphically violent and tense films I've seen. http://www.youtube.com/watch?v=UPzhtH6B5hM

Audition is a Japanese horror film that demonstrates that Ringu and The Ju-on were children's films.  The smile on the woman in the trailer is the creepiest thing in the whole world after you know the context.  http://www.youtube.com/watch?v=yhsrsWcEspc

Good viewing, all.  I'll probably add to this list later when I have time.