Unanswered list should by default contain the questions I can most likely answer: areas/tags I've already asked questions about, searched or marked as favorites.
Perhaps some kind of personalized ranking could be established there. When I land at the page from Google to solve some bug, why not entice me to increase my rep with an ad-like listing of questions that I could answer on the side (rather than just list related questions)?
I'm not that much of an altruist, there always seems to be something I've got to get done. I never just search specifically for questions I can answer to pass the winter. But, if I happened to see a question when visiting the site I could answer, maybe because I just had the same issue a week ago, I'm more likely to take the time to.