From Scientific American:
http://www.sciam.com/article.cfm?id=...ness-of-crowds
The key: low profile, nonaggressive tactics. While it works for soccer/football fan violence, some of the group psychology can be applied to any forum as well.
Then again, the psychology of trolling and flaming (see:
http://www.newscientist.com/blog/tec...me-me-bro.html ) probably needs special consideration and psycho-technological tweaks to address effectively