Spooky sound effects

We're getting excited about having trick-or-treaters on Halloween because Walt is rigging a system where sound effects are triggered by people walking up to our house (a hooting owl), ringing the doorbell (a moaning ghost), us opening the door (a loud creak) and us closing the door (a goofy voice saying Happy Halloween). We tried to pick sound effects that aren't too scary, but enough to get some blood pumping. :)