One of the first things I did upon joining this site today was to go through the unanswered section (hoping I'd be able to answer one). I didn't end up finding one I felt I could answer, but I did find a great question. So I bountied it - it very quickly got an answer which deserves the bounty (I'm holding it a bit longer in the hopes of more participation).
What's to stop some of the other higher rep users adopting a question they like and offering a bounty?