The recent implementation of a -5 karma penalty for replying to comments that are at -3 or below has clearly met with some disagreement and controversy. See http://lesswrong.com/r/discussion/lw/eb9/meta_karma_for_last_30_days/7aon . However, at the same time, it seems that Eliezer's observation that trolling and related problems have over time gotten worse here may be correct. It may be that this an inevitable consequence of growth, but it may be that it can be handled or reduced with some solution or set of solutions. I'm starting this discussion thread for people to propose possible solutions. To minimize anchoring bias and related problems, I'm not going to include my ideas in this header but in a comment below. People should think about the problem before reading proposed solutions (again to minimize anchoring issues).
Consider the prior art, here. The first place I saw the "reply to any negatively-scored comment inherits the parent's score" concept was at SensibleErection. That policy has been in place there longer than LW has been a forum (possibly longer than reddit), so it seems to work for them.
Prior art for special "oldschool/karma-proven" sections: hacker news. Paul Graham is intensely interested in keeping a high-quality forum going, and is very willing to experiment. Here's the normal frontpage, here's the oldschool view, and here's the recent members view. Hacker news also has several threshholds for voting privileges.
One more step HN took is hiding comment scores, while continuing to sort comments from highest to lowest. It's dramatic, almost draconian, but it definitely had an effect on the karma tournament system
As far as I understand, the "noobstories" list is all the articles submitted by new accounts in reverse chronological order, while HN Classic is the current front page sorted according to the votes of "old" members.