A. "flag" for comments? Whether that just brings them to the editor/moderator's attention, or kills them based on some algorithm, would be an open question.
B. More moderators/editors - drawn from the pool of people who have shown themselves to share the "HN spirit" (or whatever you want to call it), who are empowered to kill stories and/or comments.
And maybe some limits on what new accounts can do? Maybe go so far as requiring new users to lurk for some period of time, before being allowed to post? Or some limit on post / comment frequency, until you've demonstrated some sense of alignment with what's appropriate here?