I once worked in a hospital where the room right across from the nurses station was haunted. It was a double room, and bed A, right by the door, was very active. We switched beds in and out multiple times, but they would all raise and lower by themselves, both as the entire bed, or into high Fowlers. The call light (no matter how many times we switched it out) would go off several times a night. If there was a patient in either bed, nothing ever happened. Also, if it rained, the window in the room (beside bed B) would open on its own. It was on the second floor, so the window was very heavy and you had to slide it to the right to open it. I once closed it, while wind and rain were blowing in, only to have it re-open before I could get out of the room.
I also saw a man one night while sitting in the nurses station charting with the CNA, who was working on the diet list for the next morning. The station was a corner of two halls. The man, dressed in a dark suit, walked into view and then was obscured (or should have been for an instant) by the wall of the corner, before turning left and going down the other hall. There was a window the length of that wall of the station, and the only option was for him to turn left. When we didn't see him again through the window, I jumped up and looked out. There was nobody there, nor in the only room he could have gone into.