Is there some sort of advanced search that will let you search for questions that have some number of comments but no answers?
Chuck's idea from this post made me wonder about an admin tool that can find questions that have been answered with a comment. Then presumably the admin can move the comment to an answer, write their own answer, or encourage the original commenter to post an answer.
Perhaps there is a developer back-end that allows scripts or bots to do this kind of thing?