I've been systematically going through old unanswered posts and flagging any that aren't answerable. There seem to be a lot of borderline posts where the post is not amenable to interpretation as-is, but could be, except the post is old and the poster hasn't been seen for months. Other posts are only partially answerable, and tend to feature such partial answers as comments. These seem to drive a good chunk of our unanswered questions ratio, and we ought to go through and clean up.
There's only about 140 unanswered questions, so even if we can just shave off 10-20, that would make a respectable dent. If you've got a free hour, please give me a hand.