I recently learned how to create a the Pepper's Ghost illusion. I've been going crazy with it ever since. This is a small Halloween box decorated inside with a 1/4 inch scale miniature haunted house scene. Notice the tiny haunted phone with the receiver floating in the air like a ghost has decided to make a call. There is also a small crystal ball and a frightened cat with its back arched. The room is rigged with working lights that turn on and off. When the lights come on, a small transparent ghost appears in the room. This illusion is hard to capture on film. If you look at the very last of the pictures above, you can barely see her materializing in front of the fireplace.
(Click on the pictures to view up close.)
The ghost illusion is accomplished by placing a piece of slanted plastic in front of the scene as you see in the photo above. The real ghost is hidden in the lower left hand corner so she can not be seen when peering through the window in the front of the box. (see photo below) When the lights come on, her reflection appears on the plastic, making it look like there is a ghost appearing and disappearing inside the room.
It looks much more amazing when viewed in real life, when the box is dark and everything is lit up with tiny internal lights.