Evil Dead 1 and 2 as mentioned.
"Zombie" by Lucio Fulci
"Seven" was freaky, although not strictly a horror movie
"Wrong Turn" was excellent
House of 1000 corpses was good too
Classics: frankenstein
Son of Frankenstein
Dracula
Frankenstein meets the wolfman
there are so many good ones
(major horror fan here)
check out this site for all you horror movie buffs:
http://www.joblo.com/arrow/you will LOVE it for reviews and horror talk.