I think its best if some users are moderators without behaving like moderators. Without anyone to know. And all they do is move threads to the correct forum and perhaps fix a typo in a subject, or make a subject more accurate. This kind of behaviour. If a user really misbehaves they could be send a warning by PM or e-mail by the moderator team. If you keep the moderators anonymous you also keep the relations between people on a similar ground, and the bad guys won't be able to know when or who to flame/troll.