Earlier in this thread someone recommended
Drag Me to Hell....I endorse this one. Cheap scare tactics but it works...believe me

My endorsement also for the following:
The Mist and
The Descent x2
Wheelbarrow recommended
The Audition...x2
Not sure if this was mentioned before but you should definitely watch
The Shining.
Also, I see that you already looked at
Night of the Living Dead...let's hope it was the original black and white version from 1968 bc IMO it was better than the remake!
Zombieland and
Shaun of the Dead...horror with a comedic twist...maybe not what you're looking for but they were really good movies.
Sweeny Todd:The Demon Barber of Fleet Street....horror with musical twist....again might not be the purist's choice but it was another good movie. Johnny Depp ftw

Another good....actually GREAT movie if you haven't seen it is
American Psycho....if you like horror flicks you'll love this....but it's a thriller not really horror...I hope I'm not going off topic too much but when I was looking over my movie files, this one was in the same location with the true "horrors" but it's a winner for sure.
New recommendations -
Room 36 and
Let the Right One InThat's it for now, but look out for
Paranormal Activity 2 and
the Last Exorcism...soon to be released...I'm hopeful for these two.