Im a pretty big fan of movie scores. I pay a lot of attention to them when I watch something. A score depending obviously on how good it is can ruin a very good film or save a bad one for me.
Favorites:
Ravenous (Listen to this one all the time)
Jaws
Psycho
Once Upon A Time In America
The Shining
Good, Bad, Ugly
Predator
Star Wars
Godfather
Alien 1, 4 (Resurrection soundtrack = best of the 4)
The Thing (Nominated for a razzie award but I still like it)
Deep Red
Dirty Harry
Signs
Shawshank Redemption
2001
Taxi Driver
Species
Hellraiser
Saw
Requiem for a Dream
Schindler's List
Dagon
Dracula 1992
Philip Glass's new version of the 1931 Dracula

Goblin Soundtracks, as others have mentioned.
Louis & Bebe Barron's soundtrack for Forbidden Planet- it was a landmark recording in electronic music.
Vic Mizzy's score for The Night Walker
Donnie Darko
Krystof Komeda's Rosemary's Baby
Morricone- just about anything
Jerry Goldsmith was very prolific and wonderful
Same with Les Baxter
And Tangerine Dream
V for Vendetta
Akira Ifukubi did a lot of amazing work on Godzilla movies
Shino Sato for the original Ju-On

Psycho
The Strangers
Candyman
Halloween
Dawn of the Dead
Suspiria

Candyman, good call. Didn't hear or see The Strangers yet.
Dawn of the Dead. Which one?

Music score=
Requiem for a Dream
Halloween
The piano which is being played on the menu of Inside (2007)-Beautiful!
The Last Samurai

I still listen to these every now & then
The Crow
Danny the Dog
Queen of the Damned
Silent Hill
Tomb Raider

Rock and Rolla looks like something I may have soon...

The Good the Bad and the Ugly
Waking Ned Devine
Office Space

The Lord of the Rings (all three movies) - Howard Shore

Harry Potter and The Sorcerers Stone, Harry Potter and the Chamber of Secrets, Harry Potter and the Prisoner of Azkaban - John Williams

The Man With No Name movies (Ennio Morricone)
The Big Gundown (Ennio Morricone)
Planet Of The Apes (Jerry Goldsmith)
Anything by Bernard Herrmann, especially A Journey To The Center Of The Earth, Mysterious Island, and The Seventh Voyage Of Sinbad
Cider House Rules
The Piano
Any Beatle movie