Do you believe in ghosts?

Its one of those questions I don't really have an answer to, as is with most paranormal type things. The possibility of it fascinates me; the logic of it discourages me, but as most people I've had some things happen through the course of my life that lead me to believe there may definitely be some type of spiritual force that roams around that can't be explained. Several times, in my place, my cats have all been what appears to be watching something as it crosses the room. What it was, I have no idea, but it obviously wasn't here to do harm whatever it was. Bill Pullman did a great job in the movie version of Casper...the friendliest ghost of all :)