@rune
There was a torrent that was at 0% in my client for over three years, and as far as I could find the file didn't exist anywhere else on the internet (including some invite-only FTP sites…) other than this single torrent. But somehow, earlier this year a single person appeared out of the blue and seeded the torrent until I was at 100%, then disappeared again almost immediately after.
Naturally I've been diligently seeing said torrent since. Still completely mystified as to why and how it happened…