I've seen behavior on some "other" social news-type sites that suggests that there is a huge psychological gap between 1 and -1 karma on a comment. It seems that the first few downmods on anything greatly increase the likelihood that the comment will get downmodded again because the groupthink factor comes into play. Thankfully, on HN I think we tend to have more independent thinkers so it is somewhat less of an issue.
I've seen that work in some cases. In other cases it encourages trolls to post enough times that they can't be downvoted more.
HN has the flagging system in place, though, so this might be worth a try. The Achewood community gives you more downvotes ('lames') the more upvotes you've received, though that might encourage groupthink.
