Some lists you might want to check out:
This one is the Official Horror.com Top 100. Flayed (a member here, if you havent ran across him yet) put this together awhile back...he polled us and these are the films that were voted as the 100 greatest horror films of all time:
http://www.horror.com/forum/showthread.php?t=22953
Now this next one is a little different...its "The Unsung, The Underapperciated & the Bizarre: the 'Other' HDC Top 100". Basically, everyone sent in a list of their favourite obscure horror flicks, and 6 judges (myself included) narrowed the list down to 100.
http://www.horror.com/forum/showthread.php?t=26771
Between the two, Im sure you'll find
tons of gems that you havent seen:)