We have http://meta.askubuntu.com/questions/3053/what-are-common-canonical-questions-for-our-site, but I'm not sure how up-to-date that is. Also, there's the FAQ. Which one have we said is the official canonical questions list?
Also: can we feature that more prominently on main? Maybe a link (you may want to check canonical questions instead of answering) below the answer box?