I echo valleyofthedolls’ recommendation of The Descent.
I’d also recommend the Spanish film [rec]. Not only because of the film, but also that lead character is one of the most beautiful women I have seen on film. Not that your wife will be bothered by that.
Amityville II : The Possession. Underrated and vicious classic, produced by cynical filmmakers who have no mercy on the audience.
I’ve rarely watched horror movies because I am a big coward. But I really got freaked by Trilogy of Terror (the one with Karen Black if theres more than one)
though if you want to freak your date out, I would suggest Desperate Living.
The original “Halloween,” hands down.
A vote for both The Descent and Dog Soldiers (both directed by Neil Marshall). I especially liked The Descent. It was creepy scary but it also had a lot of depth (pardon the pun) and suspense. If you are offended by bad language though, don’t bother. It is peppered with f bombs throughout.
The first two original Omen movies are terrific!!!
I used to watch horror movies all the time, but now I only watch them in the day time or with a friend. The one movie that scared the bejesus out of me that I cannot watch again is The Exorcist. Saw it the first time when I was 13 (TV-13 version on TV) and it is just so unbelievably wrong and horrific. Still cannot watch it as an adult. 
Big improvement. I noticed after he removed the soccer ball that there was a round blurred/smudged area left behind. It might not be noticeable unless one looked for it.
Sorry. ignore the last post. That was meant for a photoshop thread.
I can’t recommend this last one. It’s a very poor Scottish remake of a classic Stephen King story. Instead of croquet mallets, Jack just kicks everyone in the shin to death.
I do have to echo the recommendations for Paranormal Activity. If I think too much about it even now, after seeing it so long ago, I still get the willies. The thing is, I don’t believe in the supernatural, and it still got me.
If you want some old school horror, try Tales from the Crypt. No, not the campy HBO-based movies. This one was made in the 1970s and is composed of several horror vignettes.
The most recent thing I can think of is The Exorcism of Emily Rose. I think it’s a better movie than The Exorcist.
I’m assuming you’ve seen the original Salem’s Lot. It had its moments.
Although not so much scary as tragic, I love the Charles Laughton version of The Hunchback of Notre Dame.
If Hitchcock’s Psycho hasn’t already been spoiled for you, it’s the one I’d recommend over all others.
I tend to be affected more by people who are about to get into trouble (caught in an uncompromising situation like illegally searching an office) than more strict scariness. As a kid, who was fairly unaffected by films such as Alien, I was scared by the original Amityville Horror and Poltergeist. Paranormal Activity has to it’s benefit verité, but it’s similar to Blair Witch in that respect. As an adult, I was most affected by The Ring (US), and for some reason Jeepers Creepers kind of got to me.
I think the key here might be to figure out which movies scare you, and then we can analyze which aspect of horror and/or suspense movies push your buttons in particular.
For example:
Pure suspense - anticipation that something bad is about to happen, whether it is violent or merely being caught.
Gore - blood and guts.
Verité / gravitas - the depiction being realistic enough that you have empathy for the characters.
Something else…
While waiting for more information, Salvage is pretty good. It’s not a slasher flick, despite the synopsis. It’s one of the few movies I’ve seen in the past few years that left me a little unnerved.
Try to avoid scrolling down to the comments, as the comment titles on that page right now contain spoilers.
Yes, my pick would be Poltergeist as well. It’s something about that movie that just makes the hair on the back of my neck stand up in certain scenes. I first saw it when I was about 14 in the theater. And I agree with people who think that “seeing” an actual monster is more of a letdown most times than the psychological aspect of thinking “what the f could be out there?”
And for some random, cheesy reason, I was really creeped out by "Fire in the Sky. For days after seeing that movie in the theater, I could not go out by myself at dusk.
Probably the needle in the eye scene. The ick factor on that was off the charts.
Definitely suspense.
gore doesn’t bother me too much because my brain just can’t shut off as easily as others. however, like i said before, certain gore is just too much for me - specifically the needle pit and the achilles tendon swipe. The exorcist needle eye scene didn’t bother me too much, and neither did a lot of the other freaky stuff. (crucifix scene was cringeworthy, but not scary or especially offputting).
however, i think the verite and the suspense go hand in hand. without believability, i’m definitely not as engaged and without my full attention, i can pretty much shrug off anything. as for blair witch, i started to get sucked in but halfway through, the 1st person camera footage was just too much of nothing, and i got disengaged quickly. from the previews of paranormal activity, the camera shots look completely different so maybe it will scare my pants off.
also, ditty jeepers creepers even though it completely contradicts this entire post. i guess the parallels to the mythic jersey devil, and the cinematography set it apart from other monster movies.
anywho, to who cares, i watched Poltergeist and it was freaky deaky. good call. i wasn’t scared to the point of losing sleep, but it did leave me with a longer tingle than i had after watching the Ring. (one of the few tingle movies i’ve seen).
lots of suggestions in this genre, and i think after the positive experience with poltergeist i’m going to give other scary movies that have passed the SDMB seal of approval a chance.
Body Snatchers, Dog Soldiers, and Paranormal Activity are in queue.
btw, thanks for all the responses. it’s nice to have some decent suggestions other than “Saw VI” and “Cloverfield” like my buddies offered.
I can’t enjoy movies “based on a true story” which actually aren’t. Especially Amityville which was proven to be a total fake. I also didn’t bother with the Emily Rose story which I don’t believe is true. Now Excorsist was semi-scary, but not really. Nor was the remake of Amityvlle.
The Shining scared me to death because of the bathtub lady, but I’ve said I’m afraid of ghosts, and will elaborate to add I’m especially afraid of the ones that look like corpses.
Paranormal Activity was ruined for me because I saw a totally scary clip online that freaked me the hell out. So in the theater, I spent the whole movie hiding my eyes when it looked like that scene might happen. It happened at the VERY END, and WAS THE ONLY SCARY THING IN THE MOVIE.
Poltergeist scared me when I was 13, and not for the ghosts, but for the face ripping scene and the chicken with maggots. (You said you saw it so I didn’t use spoiler boxes.)
I feel that way about Misery … it is the stuff that could possibly happen that is the scariest, not the stuff that is imaginary [and even though I have had paranormal experiences, I consider any paranormal in movies as imaginary]
I do not like the “torture porn” movies like Saw and the ilk, as was said so eloquently by Valleyofthedolls:
I like psychological horror the best, but sometimes a bit of blood and gore is ok like in Prince of Darkness or even Evil Dead [which I see as more comedy than horror to be honest.] I found Psycho to actually have stood up to time well, with the caveat that you have to somewhat understand the time. You can not watch movies from 30 or more years ago and expect to use todays society standards with them [a nooner with your boyfriend? no big deal, just make sure to get back to work on time … back then - the horror of unwed/premarital/extramarital sex!!1!1eleventy] Though that also goes for nonhorror movies as well 
If you’re both Stephen King fans then I can recommend The Mist.
I watch horror movies with a certain young lady, every Wednesday night. The scarier the better, because when she gets scared she leaps into my arms and stays there - so I’m always on the lookout for recommendations. The most effective so far have been the Japanese versions of:
I know the OP doesn’t like subtitles, but fucking hell the originals of those two movies are off the freaking scale frightening compared to the Hollywood remakes. Both elicited the most effective terror effect in me of any movie I’ve seen before. I cannot recommend them highly enough - and in my experience they’re so good that you forget you’re reading subtitles about five minutes into the movie.
Has anyone else seen the Swedish vampire movie Let the Right One In? That’s not scary really, just bleak and sad, but it’s a very good movie.
I think what scares a person is a very personal thing like what makes you laugh and what you find sexy and what scares you at one point in your life may not bother you later. Personally I don’t find killer dolls scary or little kids to be scary. So your mileage may vary but…
28 Days Later
Shaun of the Dead and Hot Fuzz both had scary parts.
The Twilight Zone episode The After Hours has me looking very closely at mannequins to this day.
Misery and Silence of the Lambs are both very scary.
Dr. Chilton is the scariest person in Lambs. Just like Nurse Ratched is the scariest person in a movie ever. (One Flew over the Cuckoo’s Nest)
Don’t get me wrong. I love gore. Gore is wonderful but it has to be done right. If I had to point to the one thing the directors of movies like Saw and Hostel do wrong is that they try to shock the audience. Me? I don’t want to be shocked, that grows tedious. I want to be scared.
And in Psycho (which IMHO, is one of the best movies ever made and not dated at all), the scandal factor is not sex out of wedlock but rather that Sam Loomis, Marion’s boyfriend, is married.