I feel stupid actually telling people about it, but I'm pretty sure there was the ghost of a man in my old house (recently moved, while I was in school, so I don't know about the new house) who would just watch. I'd see him out of the corner of my eye all the time, especially when I was home alone. Never face on, though. He was really tall and I got the impression of him being old and had sorta long hair.

As for the premonitions, I get those a lot but it's always about small things. It's like déjà vu but more intense and less vague.