When ten_fifteen filled out the survey, she alluded to a few experiences she couldn't quite explain away. She and her husband (alltimeqb) are rational, reliable people, as far as I know, so I prodded her into relating some of these experiences, and they are genuinely creepy and pretty difficult to account for.
So, the rest of you: do you have any such encounters? Let's do a forum on this. I want only first-hand ghost stories, stuff you personally experienced, not a tale handed down from your grandfather or your mother-in-law (even though those may be cool). Also, feel free to do your best at explaining it - e.g., "But then, I was looking through a pane of glass, so I suppose it could have been a reflection..." - just to make this as scientific as possible.
Banshees, poltergeist, telekinesis, and other strange earthly phenomena are fair game, too; it doesn't have to be an actual visible "ghost." But let's leave Bigfoot and UFO's out of it. We'll do that another time.
P.S. Kev or Kim, say the word and I'll remove that link (and/or your names). You needn't be an exhibit if you don't want to be. :)