If you threw $100 at the post right in the first second, then the curation rewards would go to the author..
IDK, the idea itself is very cool, but unfortunately (IMO) it opens up way to ways for users to game the system. The amount of complexity that would need to go into a formula that could not be abused would make it very difficult.
I really like the pure tipping idea that is being discussed, with a separate balance that only needs your posting key to use.
Well, if it can't be done, so be it. But a tipping option should still be on the post, even if not added to the payout. I can't think if any reason why it shouldn't be.