Great thread! I'm just a newbie, but I do have one suggestion: "thread posting privilege suspension."

How this might work is as follows:

In every thread post, there could be a little "I object!" button that a viewer could click on if they find that particular post offensive or off topic. If enough people click on this button, then that particular poster is "blocked" from posting any further posts in that particular thread.

And to prevent the button from being spammed, require that each person pressing the "I object!" button enter their username and password, and click on a choose-one option as to WHY they objected (eg: off topic, offensive language, improper debate tactics, etc. etc.)

When enough people have objected (ten? twenty? thirty?) then the person with the objectional posting is blocked from posting again in that thread, but will have access to anonymous poll results as to what was objectional about their posting.