There is one particular person I have unfriended about 5 times. Unfortunately, we have something like 60 friends in common, so whenever he sees my posts/comments/etc. on our mutual friends walls, he friend requests me again. Facebook probably keeps re-suggesting me to him as well, since we have so many friends in common. Initially I would accept, wait a few days, and then erase him again, but now I have left him permanently in "request" limbo. Most of the others I have unfriended simply disappear.

I also blocked most of my dad's posts. He gets outspoken and occasionally no sense of humor and it was just too much. Unfortunately, he sometimes asks if I saw XYZ on facebook (pics of house, etc.).