I run lots of forums, on many technologies, and the only way that I've achieved long-lived peaceful forums is to have virtually no moderation and no moderators.

I run lots of forums, on many technologies, and the only way that I've achieved long-lived peaceful forums is to have virtually no moderation and no moderators. As soon as you have moderators, the users defer responsibility for confronting the bad stuff and it represents the start of the decline, "If that was allowed, why isn't this?". Without moderation, and with the community possessing some tools to enforce, most communities will take on that responsibility and do so. i.e. the flagging on here or on Craigslist that allows multiple people to moderate where an individual's signal is weak but collectively it becomes strong. Of the course the only thing that this doesn't address is broken group-think across the whole forum. To that, I've found making the admin of a forum the legal buck-stop for the forum works well. This is compatible with EU law, where you generally need someone to be responsible for complaints of a libel/defamation nature, and so I designate the forum owner as that and I move myself into the "mere conduit" role. This method of "everyone is a weak moderator, we have no strong moderators but we do have a strong leader who is liable" has been very effective at producing decade old, healthy and growing communities.