If you have run out of original Halloween decor ideas, take inspiration from the Friedrich Van Schoor Projected Spider Battle. The German artist filmed spiders in a miniature replica of an office, and then blew up that video and projected it onto a real building. The result is the illusion that humongous mutant spiders are attacking each other in a regular old office building. They must be just waiting for a young teen to walk into the room, get bitten, and turn into the Amazing Spider Man.
This clever and creepy art project stands miles above putting out some Jack-o-lanterns on your front porch and calling it a day. If spiders aren't your thing, just think of the possibilities using the same technique.