I like the idea of allowing users to put out bounties on other people's questions to help this out. This may make things more worthwhile to research and answer. A few caveats to this:
1) Multiple users can put out bounties on a question, however should anyone who has put out a bounty answer the question as well, they are prohibited themselves from collecting on the bounty, they can still answer the question though, and if they are marked as the answer the bounty points outstanding disappear to the eternal void.
2) Only the original person who asked a question can still mark an answer and award the combined bounty, no matter what.
3) A certain amount of reputation should be earned before you can put out a bounty on other people's questions (say 1,000 rep). This will allow for a "master presence" effect drawing more experts to the question.
EDIT: Another idea, how about allowing "abandoned" questions to be answered by the community, in the case of where the person who asked the question never shows up again? Or I'd set it up something like this:
If the question is unanswered, AND it's been 3 months since the person who originally asked the question has visited the question then open the answers up to a community vote. As soon as 10 people vote an answer as "the answer" that question is given the "answer" award, and all the requisite reputation, bounties in effect, etc. Now then, we put a little at stake for the voters to ensure their honesty and that they've researched it. For every upvote obtained on the answer AFTER asking, the voters gain 10 reputation apiece, however for every downvote obtained on the answer after asking, the voters lose 5 reputation apiece. The voters who marked as the answer are confidential to remove bias in this.