I've been using Contributor for the last month or so: 1) One needn't turn on all third-party cookies to make it work. Enabling a subset of [*.]doubleclick.com, [*.]doubleclick.net, and [*.]google.com is sufficient. 2) Contributor is the best existing solution to the third-party micropayment problem I've yet encountered. Direct contributions to sites are surely preferable, but not yet practical. Contributor would appe…
I'm not sure that it is rent in the economic sense. They're providing one place to sign up and pay, and then distributing the money in a reasonably fair way. That's actually a valuable service.
I find that there are a lot of sites that I visit infrequently enough that I don't want/need to sign up for their service, but I still like to see the occasional article. For example, I read Economist articles when I see them linked. I don't want a full-on subscription, or even go through the hassle of creating an account, but if Google can throw them some cash on my behalf I'd be happy about that.
IIRC, the problem with a lot of micropayment schemes was that they never got big enough for critical mass. Perhaps Google has managed to do that by way of ads, and maybe they'll develop into what those schemes always wanted to be.