via Little Green Footballs:

But they delete it in a sneaky way; when you visit the page and are logged in to your account, you still see your comment, but everyone else sees either nothing or a message that the comment was deleted.

I love it, honestly. I know it’s underhanded and sneaky and I would never use it on someone criticizing me or with something I didn’t agree with, etc. However, this is the perfect way to deal with a Troll. Anyone who’s ever run a site or especially a forum knows that banning by IP is about as useful as asking the troll to stop in the first place. Same goes for banning their email address. They’ll be back before you can refresh your page. The idea of making it look deleted to one user isn’t new. vBulletin actually has that feature built in. It’s called Tachy goes to Coventry and it works remarkably well. Tachy lets the user continue posting and responding but only Admins and that user sees it.

This would make a great Wordpress plugin. Have it support either Cookies or Logged in users and you’d have a great tool to add to your arsenal to defend against trolls.