actually, something much simpler would be along the lines of 5 users click a "veto" link on the post. Once 5 users have "vetoed" a post, an email is sent to the admin and/or mod of that forum, or something is showed in the CP, which contains the URL to the thread, and the users who "vetoed" it, possibly making them fill in a reason for the veto would help, but I think most people wouldn't bother
that way it doesn't actually get removed until an admin/mod sees it