Something for a Halloween Showing...

I'm thinking of setting up a little party/showing around Halloween so I wanted suggestions for good horror themed anime so I can check them out in advance. Being genuinely creepy or scare inducing with good writing would be a plus. Also, since there will probably only be time for 1-3 episodes per series, a strong beginning would be preferable.

Highschool of the Dead is already on the menu for sure. =)

Anime already seen and under consideration:
Higurashi
Hellsing
Monster
Petshop of Horrors
Puppet Princess
Vampire Hunter D (both films)
Death Note
Boogiepop Phantom
Blood
Perfect Blue

Anime currently being watched and appraised:
Shiki
Ghost Hunt

Thanks in advance for any new leads and your time. =)