It seems there's a lot of unanswered questions with good answers, but no up votes or OP's activity. I think we could use a closing reason allowing to:
- Close an unanswered question older than 15/30/60;
- Check if the question has a not-so-bad answer;
- Check the OP's recent activity, and:
- If recently active, ask him to comment the answer or edit the question to make it better;
- If inactive (15/30/60 days), automatically close the question as "Probably Answered".
The unanswered list would be shorter and more accurate.