I just clicked on the "Unanswered Questions" tab, and was surprised by the number of questions that had no answer (I was trying to find some easy ones to boost my rep). Is there more of a mechanism than offering bounties or editing questions to get these unanswered questions some traffic? Perhaps a "featured" unanswered question by the mods? (Can they even do that?).
The figure "410" by itself needs context.
At the time of writing 90% of questions garner an answer, and this is considered "Okay" (for a beta site). It has been an area where we have had trouble in the past keeping up with other StackExhange sites. I just looked at a couple of examples which I thought might be like Skeptics.SE: Physics.SE gets 96%. English Language Usage.SE gets 100%!
There are several existing mechanisms for attracting attention to unanswered questions:
As you found, the Unanswered link at the top of every page and again as a tab under the Questions page. It is a good way to find questions that a lot of people are interested in, but that haven't attracted an answer.
Hint: By this stage, the top few questions have been combed through several times and are known to be difficult to answer. You might have more luck starting on the second page.
Every now and again, ignored questions are randomly selected and popped to the front of the queue. (Generally indicated by an edit by "Community", where no edit has occurred.)
At least, this is what I was informally told. There are other causes to edits by Community, and I have never seen the original feature described.
The Bounty Questions page (found under the "Featured" tab on the Questions page) includes the unanswered questions that people feel strongly enough about to dedicate some of their rep to encourage a good answer.
Hint: I notice people eager for their answer offer a bounty very soon (a couple of days) after answering the question. This isn't the most efficient use of the rep (if that is what they care about), as many people will not have seen the original question yet.
The Greatest Hits page is not well advertised. It includes the questions that garnered the greatest amount of views and feedback. If you want to your skills at copy-editing and clarifying poor English to go the furthest, these are the questions to tackle. Also, some of them remain unanswered.
The Skeptics.SE Newsletter includes links to several currently unanswered questions.
Pleading from the Mods - (Hat-tip to @Tom77).