This just might be the future right here. I wonder what would happen if everyone, upon signing up for medium received a certain amount of ‘M’ tokens (insert your name for tokens here) that one could use toward micro donations to authors. Then to refill your account you’d use real money to purchase more. Then everyone could make a micro donation with one easy click.
Perhaps sponsorship would be a level higher where all sponsors would be added to a sponsor bar at the bottom (if they want credit for sponsorship), like you have done.
The hard part is making this so easy that each only require one, or maybe two at most, click(s).
There is something here.
Ev, are you listening?