As far as I can tell, the unanswered questions broadly fall into these three categories:
- Really hard questions/Questions in niche topics: These can be answered with some research, usually, though sometimes you really need a topic expert. I've seen @Amaterasu and others do this at times (Your effort is appreciated!)
- Questions which are easy, but just didn't get enough attention at the time: These need someone with a bit of time to come and give a good answer.
- Questions which have good answers, but the answers aren't upvoted: The solution here is clear, vote vote vote! But only do so if you would have voted on that answer normally as well, don't just vote on iffy answers so that the question is removed from the unanswered list. If you find something with an iffy answer, add your own, better answer!
So, while it is clear how to fix individual unanswered questions, any ideas on how to tackle this as a whole?