A bounty-like feature for challenges
Sometimes, challenges are so well-designed and/or have taken so much effort, that I want to give the author a bunch of my rep for the great service they've done the community. Currently, the best/only way to reward a challenge is to put a bounty on it to attract more answers (and maybe some more votes because of the additional attention) and to share it off-site e.g. on reddit or Hacker News.
It would be great if the software provided a way to reward our most dedicated challenge authors more directly.
I'm saying "bounty-like" because it probably doesn't make sense to put them up for 7 days and say "this will go to the best challenge which meets criteria X, Y, Z". These would either be indefinite bounties ("first well-defined challenge that pulls off an audio-to-image processing task") or could just be given to any challenge on the spot (maybe also featuring it, like a normal bounty would). Of course, one would have to carefully think about whether and how this system could be gamed.