I'm a big fan of forums. I like having an opportunity to discuss things with folks I might not run into otherwise on a regular basis. Similar interests doesn't necessarily mean like minds though. A forum with atheists and Christians is a lot more lively than one with just atheists or just Christians!
I participate, or have participated regularly in the past, on forums for caricaturists, Knife Aficionados, graphic artists, Mensans, cyclists, atheists, web masters, as well as others.
We lose a lot when we try to communicate anonymously with no body language. Especially when we are dealing with people with unlikely names such as SpaceMonkey101, BluBolz68, and JCreanimator2012.
Not knowing if someone is really an angry pimply-faced thirteen year old troll or a Brazilian supermodel throws a lot of social norms out the window too.
How do we treat each other in on-line forums that are filled with trolls, fanatics, perverts, pedophiles, cyber-bullies, and other miscreants?
Robert Heinlein said, "An armed society is a polite society." On some forums the Liberals have won and its' citizens are all disarmed and castrated. The only modicum of power is held by the moderators. Its not like real life where people who actually have common sense realize making certain statements will get them a quick shot in the chops. There the Socialist Collective allows the bullies to run rampant for the good of the whole. If someone is rude but sneaky and profanity-free, they have nearly complete immunity. If someone is being a douche and you directly and politically incorrectly suggest they perform anatomically improbable acts with themselves, you will most likely be chastised and ostracized.
"Political Correctness is tyranny with manners." - Charlton Heston
With genuine problem children, we can run and tell forum moderators, use readily available software to get people's IP numbers and run and tell their ISPs, or get our hacker buddy to ruin their dog's credit. And lastly, we can realize forums aren't mandatory, walk away, have a beer, and go outside and play.