Here are a few online lists of best horror films:
IFC has a list of the scariest moments in non-horror films. I'm surprised that the human sacrifice of Indiana Jones and the Temple of Doom isn't listed since it does include the climax of Raiders of the Lost Ark. Check out the full list here.
On The Daily Beast, Martin Scorcese picks his favorite horror films. Most are supernatural or haunted house films like The Haunting or The Exorcist. I wonder if this reflects his Catholic background. Check it out here.
Entertainment Weekly has a list of the twenty best horror films of the last twenty years (1989 - 2009). I'm glad so see someone else appreciated Event Horizon (one of Paul W.S. Anderson's few redeeming films) and Hostel Part 2. Check it out here.
BET has posted a list of horror films with black actors in a lead role. That the Saw films include a diverse cast never occurred to me until reading this piece. Check it out here.
Examiner.com has a list of obsucre horror films that they feel should be more widely appreciated. I have to admit that I haven't seen these. Check it out here.