A buddy of mine sent me this link to a video clip. At first it appears to be a really good clip of proof of a ghost that is making the rocking chair move all on its own.
But if you look really closely, you can see, just to the bottom left of the leg of the chair, that there is a string being used to pull the rocking chair and that is what is making it rock.
It's tough to spot, so you have to look really closely - the screen flickers for a moment, then you can see the string being pulled.
(Click here to go to You Tube and see the video.)