Sure. I do not want to go into detail right now on what mechanisms strike me as the most likely to work, so let me just suggest that a better system looks more like the "procedural law" used by our courts. I will also say that Less Wrong does not use a technique (namely, refraining from pursuing unrestrained growth in membership) to protect the quality of the conversation that seems to have served well the group blog Hacker News.

I think it is rational to avoid taking on an ambitious goal at this point even you do not believe that I know of better mechanisms for protecting conversations than those used on Less Wrong.

ADDED. Before we talk about how to improve Less Wrong, we should talk about why Less Wrong is better than any other online conversation for some reasonable definition of "good".