I was thinking that maybe you could add people you don't like to a block list and then they can't comment on your profile, and you can't comment on theirs. They would also get a email notification it that happened.
Well, I think that the blocking feature is a good idea, but I don't think you need to be blocked from commenting on their profile (unless they block you too), and instead of them getting an e-mail, they might just see a little message that says something along the lines of "User has blocked you from commenting". Another idea is adding a feature like only friends can comment or friend requests, and so on.
