Window Silhouettes: This is more of an indoor/outdoor decoration. Cut out popular Halloween shapes in black paper and adhere them to your windows. When the indoor lights are lit, the shapes will come to life.
Halloween Window Decorations ideas to Spook up Your Neighbors. One of the funniest and least expected things I've seen yet, but IT WORKS. I may steal the Halloween decorations idea for my haunt this year.
In the (Halloween) Window: The Great Pumpkin at RL Kids