I tried this topic a while back Geo and it was poorly received, so I apologize for the story being short. I think I saw a ghost, personally.
I woke up late at night while staying at a friend's house in my early teens. I saw a silhouetted figure walk in front of two windows that let light shine into the room from a utility light. The figure appeared to be small and short, which made me think that the figure was inside the room and not outside, because the windows were close to the floor but the wall outside continued down for another five feet. It was completely silent, and no doors opened or closed. No one else was a awake. At the time I was really startled and was afraid the next thing I heard was it trying to talk to me. It didn't though.