Luke, it is rather unfortunate that you offered a problem (How to incentivize people) and a single potential solution (use karma) in the same post, committing what seems to be a rather basic violation of rationality, something one would hardly expect from an expert in the matter.

Now, as you can see from the comments, nearly everyone has concentrated on discussing your solution, as opposed to offering their own, and the utility of your post has been greatly diminished as a result.

Then again, maybe it was your intention all along, in which case I would appreciate your thinking on the matter. (For example, maybe there was some other post where plenty of options were discussed and karma use was agreed to be the way to proceed.)