I haven't, in the physical sense, but one of my sisters, who was extremely skeptic has, and I have never seen her so scared. We were living in Florence, Italy at the time. It was a new, beautiful building of six or seven floors and we lived on the fourth floor. One summer evening she was leaning on an open window sill, as we often do in Italy, just to look at the traffic and the people strolling down the street. The window also overlooked a building, probably hundres of years old, but we never thought anything of it. I don't know if the ghost she saw belonged to that old building, but it was obviously able to float, because she saw it approaching her in mid-air. She only saw the top half of the ghost and it was, according to her description, spectral. We were in the living room on the other side of the apartment, when suddenly we heard a loud scream and saw her barge into the room where we were assembled watching TV, wide-eyed and pale as a sheet. That was totally uncharacteristic of her. Of course I couldn't resist poking fun of her because she had been such a staunch skeptic. Eventually glass water bottles started shattering in our hands, and other strange things started happening.