A cracker? xDI was banned from my own forums once. A cracker took the site, and the admin team regained it after a messy evening. The cracker framed me, so I was banned by the others until I was able to point a finger at someone else. We never found out who really did it, but...good times, good times.
I've been banned from one site (a site about a game) because the owner didn't like me, because I said that he disrespected the players. D: Besides that, nup~