Something I have noticed a lot is that new users with 1 rep ask a question and never appear on the site again. Good answers are posted, but the question stays "unanswered" forever. Often, these are perfectly good questions (I just came from this one and actually used it for recovering my system) so they don't have any grounds to be closed. What should be done with these?
You might want to consider:
(a) Adding an "abandoned" flag so that a mod can come in and somehow accept the answer for the leaver OR
(b) Adding a system for voting for an answer to be accepted, so that if someone comes across an obviously answered but abandoned question, they can vote for it to be marked as answered.
Preemptive clarification: Not a duplicate of asking or encouraging new users to accept answers. I'm talking about is people who never come back to AU.