1)For certain high-profile domains, assign no karma to submissions. This would probably a hand-curated list of domains, but would probably include: Techcrunch, pg essays, avc.com, etc.
2)Allow users above X karma (500?) to vote to give any other user a "time out". At some threshold (25?) of votes, that user is muted for 1 week.
3)For any users that submits more than 5 articles from the same domain/subdomain, either suspend karma accumulation or suspend their ability to submit until they reach some mix of other submissions with an average score above 10
4)Create an article tagging system, and/or a way for users to ignore submissions on certain topics and/or from particular domains.