Metafilter's always the example I bring up; I avoided saying it here because I think I've mentioned it a dozen times in the last week and I don't want to seem to be recruiting. (Not that I'm a MeFi poster, just a reader.)
Metafilter did a smart thing by forcing users to pay to join. It's also got the most anal modding of any civil site I've ever seen. Cortex will remove entire discussions if he doesn't like them.
This is how the SomethingAwful forums remain, in my opinion, rather high quality despite being affiliated with an offensive comedy website. $10 and strict mods seemingly breed compliance with whatever regulations you care to enforce.
SomethingAwful's the perfect example. They're the best at what they do, and their forums, while a bit immature for my tastes normally, have hands-down the most talented people there than I've found anywhere. I'm astonished at the artistic and entrepreneurial visionaries I see posting like mad there. I wish some of them would post here too.
But no community can leverage that well, because Facebook already exists for that. Adding real names to a community of strangers doesn't help much. I'm certain I've trolled under my real name before when my name didn't matter.
Metafilter did a smart thing by forcing users to pay to join. It's also got the most anal modding of any civil site I've ever seen. Cortex will remove entire discussions if he doesn't like them.