More types of flagging? 
whyme: How about allowing the primary post to have extra settings that affects what can/can't happen: Example: Min karma to post: 1000, Min Civility to post: -100 points.This way if the community sees a mob problem, the community can tweak the settings accordingly. 
I'm sure you can come up a good algorithm to maintain a  moving set of defaults.Also, maybe allow readers to filter posts based upon their  threshold settings.