I just have one ghost acquaintance in my life. It was when I was studying in collage back in India. Those days I use to stay in hostel. I was 20, and my exams where going on. Both me and my friend saw it. It was around 1 AM, we were in the study hall preparing for the exam next day. There were a few more girls in the study hall.
After feeling tired of reading, and because it was so late at night I was feeling sleepy, so just for a change and to refresh, I looked out of the window. There in distance I saw a lady in white Saari (Traditional dress of Indian ladies), she was some 5' tall, had long black hair (it was knee length long), was combing it with her fingers. The best part is, this lady was not standing on the ground but she was at top of a house, I could see her so clearly because there was light from the street lamp above her.
I blinked my eyes, but still it was there. I did it again and again, but no change I could still see her. I showed it to my friend, she too could see her. We called the other girls, but by the time they came it was gone. I should say it faded away.
The next day after our exams, we (me and my friend) walked to the direction where we saw this lady the previous night. There was nothing, not even that house. The lamp post was there, but the bulb was broken and was covered with spider web.
I had totally forgotten about this incident, but now after reading the other stories, I remembered it. I still don't know what I saw that night. Was it my mind playing trick after I got exhausted studying, but how is it possible that my friend too saw it... Guess it was a ghost itself.