an infrastructure that makes it very quick and easy mechanically and also fully socially acceptable and economically useful to make small, but still non-zero, donations in response to stuff we like.

This is actually something I'm working on! :) Other (paying) projects and a hacker attack have taken precedence, but I'm working out the gears and whistles as we speak. Though, done my way, it will be fantasy/sci fi genre, probably... I'm ambivalent about managing a free-for-all site. If the software is awesome enough, I might make it open source and let other folks spread it further.