I've heard too many ghost stories from reliable people to totally discount the idea of the existence of ghosts--including my best friend who sees spirits. She knows not to tell me if she sees anything in one of my homes, but she, along with several other people, saw her late mother at her wedding.
I'm in the "don't want to know" camp. I think if I ever had personal proof, I'd probably have a heart attack right then and there.
cookietime - I do what your husband does. It's always when I'm really stressed or over tired. It's exhausting being that creepy in the middle of the night.