My favorites:
The Return of the Living Dead (best in the series, although the second one is up there, too)
Hellraiser (the second is a classic, too)
A Nightmare on Elms Street
The Texas Chainsaw Massacre
The Shining
Pet Sematary (the second one is actually really good, too)
Night of the Living Dead (the remake; the original never did anything for me)
Dawn of the Dead (and the remake)
Day of the Dead
28 Days Later (and 28 Weeks Later)
The Crazies (remake only; the original is hilariously awful)
Scream
Evil Dead 1-2 (the remake is awesome, too)
Shaun of the Dead
Tucker and Dale vs. Evil
Quarantine
Eraserhead
The Descent
Wolf
Interview with the Vampire
Let the Right One In
The Ring
Funny Games
Hostel 1-2
Saw
The Last House on the Left (original and remake)
I Spit on Your Grave (remake; haven't seen the original yet)
Borderlands
Jennifer's Body
The People Under the Stairs
Haute Tension (High Tension)
Man Bites Dog
You're Next
May
Tales From the Hood
Tales From the Darkside
Jacob's Ladder
Silent Hill
The Silence of the Lambs
The Cell
Psycho
8mm
Untraceable
The next ones on my list are so sick that I've never watched them all the way through, which is really saying something (although I probably will when I'm in the appropriate mood):
Men Behind the Sun (the vivisection scene of the little boy is one of the most disturbing scenes I've ever seen and was very realistic, but everyone who's watched it only seems to get upset over the cat scene, which was obviously fake, for some weird reason)
August Underground series (realistic, simulated snuff films with every type of sick **** you can imagine)
(These films just make me think "dude, wtf is wrong with German people!"
)
Nekromantik 1-2
Der Todesking
