Haunted Dimensions has a free paper model of the spooky entrance gate outside Disney’s Haunted Mansion.
Invisible City Productions offers Cthulbeque, a game in which players compete to put the most Cthulhu themed dishes in their serving area.
The Haunted Dimensions site has paper models of three small crypts. The only downside of these is that the back of the crypts are defaced with site advertising. Still, there’s also a brick wall there that you can paste the crypts up against.
RPG Now has a free horror RPG module called Dead of Night: Night of the Santa Claws. It’s designed for the Dead of Night RPG, but no doubt could be modded for any other system.