My dreams have been answered! Google has released a blacklist extension for Chrome that allows you to blacklist domains and have them filtered from your search results (hattip: @pmlozeau). They've added a "block" link to their search results page to make it easy for select a site to blacklist. Google will also be aggregating all our blacklists and working the data into their search results, hopefully to identify and filter out these link farms from everyone's search results.
Of course, now the race is on for people to try to use this to game search results, knocking their competitors and anyone they don't like or agree with down results page. (I'm confident that Google has planned for this inevitable abuse of this very useful extension.)