Not everyone was a fan, but I found the use of sound in Blair Witch Project at times freakin scary. In particular, the scenes where they are sleeping in the tent, there is no light and we start to hear weird sounds off in the distance. In terms of intensity I found this film awesome.

Have you seen the innkeepers? Sound is used as a plot device in a gimmicky way but I thought it was pretty effective.

Might do you good to peruse the "Films to study for excellence in sound design" for thrillers/horrors,

but these films are what I especially liked for their soundtracks:

• The Ring
• The Cell
• The Lovely Bones
• The Shining

I'll think about it for a bit and update my answer if I come up with any newer ones.

recent sound design and mix I liked: - Girl with the dragon tattoo

In terms of recent films, I quite liked The Orphanage. I thought the sound of Drag Me To Hell was especially awful. SSD's own Mr. Prebble was involved in /oops/40/oops/ 30 Days of Night, so maybe that's worth checking out...

There are a few that impressed me in different ways!

To begin with, the sound from The Beyond (Lucio Fulci 1981) might be a tab bit crude and coarse, but here it works well! What impressed me here though is a scene where the fact that a ghost girl and her undead dog runs completely silently is heavily emphasized is something I appreciated a lot!

Froniere(s), an extremely violent and gory French nazisploitationflick, has both a really good mix and sounds with extremely nice texture and aural pain.

Which leads the Saw 4 and 5. They are a little to the bright side, but the sounds have an amazing texture to it, and is extremely well designed!

It was a while since I saw it, so I can't exactly remember what it was I liked with it, but the Korean movie The Host is in my "Good Sound Shelf", and I do remember it was for a good reason :-)

Though also, like most movies made before the advent of Pro Tools and Nuendo (I guess at least a few of you here remembers the old 35mm full-coat, reel-to-reel and NAB cart machines...), not perfection in sound quality, I really like the sound of Hellraiser! Like in Se7en (one of my absolute favorite sound-movies together with Wall-E and No Country For Old Men), I really think the grit and coarseness of the sound adds to the uncanny feeling of the movies by working with the limitations of the medium instead of against it! Something I can all too well relate to :-)

An oldie but a goodie... 1963's "The Haunting", directed by Robert Wise. Just about ALL the scare factor comes from the sound. A primer on making things sound spooky, and all done before digital - not that that makes it BETTER, just proof that a zillion plug-ins don't necessarily make good sound design.

Also someone mentioned "Drag Me to Hell", but for a much finer example of that crew (Marti Humphries and Co.) check out "The Exorcism of Emily Rose". "Hell" being a Raimi film was by necessity somewhat more over the top, while "Exorcism" plays on a more subtle note.