Have you ever seen a ghost?

I haven't seen a ghost, but I had a poltergeist in the apartment I lived in at college. Once, it threw a couple of books across the room from the bookcase that landed at my feet. I had the window open, and it was breezy, so I thought that may have been it, but when I looked at the bookcase the books had come from, there were loose papers right next to the books that were untouched.