PG: The biggest source of stress for me at YC was running HN

Can't we leverage this lesson then? If smaller groups can be integrated into the larger one with enough time, then the answer is straightforward. You can have very large internet forums, but new users need to be slowly integrated into the 'culture' piecemeal.

Create a good culture, then break it out and parallelize it. New users get slotted into larger groups to learn the culture, then they can be sent on their way into the larger culture.

Twitter Training Wheels?

Those forums exist I am sure, because ES is now an ancient concept.

I'm guessing those forums now are invite only.

Exclusivity has been one of the primary driving factors in most major social web companies... and then at some point they just open the floodgates. I think, barring the extreme freedom of speech side like the chans, a good analysis and use of exclusivity would be a great way to do things. What gives you the "ticket in" is another topic that would take a lot of thinking and would depend on the site and it's goals.

> What gives you the "ticket in" is another topic

That's the primary factor which would determine the outcome. As a community, you probably want to attract currently undervalued people and help them to uncover their potential. If it's just invite-only community, I expect it to stagnate and never reinvent itself for the better.

There are a few good public forums (like lobste.rs) which require invitation to comment, and I inevitably end up ignoring them after I want to contribute to the conversation and realize it's not possible.

Metafilter has been successful, I believe primarily due to the $5 charge to create a posting account and the warmup period of limitations for new accounts. New accounts trickle in at a manageable level. All account owners get that sense of ownership and care that comes with exchanging currency for something. Most internet brigading can't scale a small expense to begin with, and existing account owners who might otherwise get bootstrapped into a brigade don't want to get kicked out for being a jerk.

SomethingAwful has a similar requirement on spending money for an account, but that's not stopped people from doing dumb things to get muted or banned, keeping the moderators quite busy.

at least the expense can be used to fund additional moderation.

see: facebook, twitter et al complaining about moderation being too hard at scale

Doesn't Stackoverflow do that? You can't answer immediately, and so on? But something seems to be missing there as that community and culture can be unfriendly.

I go there for answers. I not longer participate. It's not worth the effort.

Same here. SO is good for answers, but I've been chased off trying to participate too many times now. The community is toxic even to people that have lurked there for a decade.