Moderation seems to have a double meaning: there's moderation as in moderation in all things and moderation as in keeping a discussion going smoothly. Actually, both of them are about the same thing.
Participation in online forums tends to follow a "power law," with vastly unequal engagement.
If you want to counteract this tendency, one possibility would simply be for the most active participants to step back, and moderate how much they speak. This is related the theCarrying Capacity pattern and theMisunderstanding Power anti-pattern: check those out before you proceed.
Occupy Wall Street used a technique that they called the "progressive stack." There are lots of other strategies to try.
The Co-Intelligence Institute: Why is a fishbowl more productive than debate? The small group conversations in the fishbowl tend to de-personalize the issue and reduce the stress level, making people's statements more cogent. Since people are talking with their fellow partisans, they get less caught up in wasteful adversarial games.
In a distributed project, there are many side-conversations, and it is impossible (and would be undesirable) for any one person to moderate all of them. The difficulty occurs if one of these conversations becomes uncomfortable for one or more participants, for whatever reason. Rather than depending on one central moderator, it's useful for everyone in the project to be aware of the principles underlying effective moderation, and apply them together even in small side-projects.
We recently ran a Paragogical Action Review to elicit feedback from participants in the Peeragogy project. Some of them brought up dissatisfactions, and some of them brought up confusion. Can we find ways to bring these concerns front-and-center, without embarrassing the people who brought them up?