Yesterday I scrolled through Unanswered Questions because I could not face doing the grubby task I had to do. There are some fascinating questions there that I think actually have answers, but not easy answers. I resurrected one of mine, and added a 250 point bounty. I might do the same with another question. But, before committing much more rep to bounties, I ask:
Is there interest in creating some kind of Contest or Event focussing on answering Unanswered Questions for a finite period (say a month, maximum ?) If there are rewards, it might be "financed" partly by users willing to contribute some of their rep and partly by SE. Maybe in conjunction with the Hat event at the end of the year?