We might want to consider methods of raising standards for community members via barriers of entry employed elsewhere (Either for posting, getting at some or all the content, or even hearing about the site's existance):

• An application process for entry (Workplaces (ie Valve), MUD sites)
• Regulating influx using a member cap (Torrent sites, betas of web products)
• An activity standard - You have to be atleast this active to maintain membership (Torrent sites, task groups in organizations sometimes)
• A membership fee - Maybe in conjuction with an activity standard - (Torrent sites, private online communities, private real-world communities, etc. etc.)
• Allowing membership only by invitation/sponsorship - (Torrent sites, US Citizenship, Law firms partnership, The Bavarian Illuminati)
• Having a section of the site be a secret, only to be revealed to people who have proven themselves, A-la bayesian conspiracy - (How classified intelligence organizations work sometimes (not a joke), Internet forums)
• Karma-based feature upgrading (Stack Exchange, Internet Forums)

Or any combination of the above applied to different sections. If anyone would like to pursue this, I am willing to spend up to 2 hours a week for the next few weeks constructing a solid plan around this, given someone else is willing to commit at least similar resources.

On a different note, and as anecdotal evidence, I have been lurking on LW for years now, and went to a CFAR camp before posting a single comment - In fear of karma retribution and trolling. (I know that its a bad strategy and that I shouldn't care as much. Sadly, I'm not as good at self-modification as I would like to be sometimes.)