There was a period in 1995 where a little girl lived in my house. I was laying in bed one morning relaxing before getting up and I heard a small girl's voice next to me say, "Mommy." It was so sweet sounding though that I wasn't afraid. About a month later, my husband of the time was fishing around in the library looking for a pack of cigarettes he had hidden when he heard a little girl ask him, "What are you doing?" Startled, he looked up thinking it was perhaps me but no one was there. This freaked him out and he promptly ran out of the house.
I don't know who this little girl was, why she called me mommy, or where she went shortly after these few incidents. I think sometimes only the ghost knows why or how they are there.