i think there are some unintended consequences with blacklist list-sharing:
1) if google ever starts using this data as a signal in their search algorithm, do you really think demand media is going to give up, or do you think they are going to start moving their content on the 500k+ domains they own, effectively making it impossible to deal with the problem.
2) list-sharing seems to be starting an arms race where spammy sites start pushing their own lists that include all of their competitor's sites but not their own. (i am not accusing the OP of doing this, but i think its best for each user to choose individually.
if these sites really have such egregiously bad content, then users should very quickly be able to decide for themselves when a site should be blacklisted.