There's this idea that's "brewing" as John Battelle says about sell-side advertising or "open ad tags" as Jeff Jarvis calls them. The idea is if you've got an ad, you just put it out on the net somewhere, tag it, and let the ad networks' crawlers come get and run it wherever.
The critics claim this scheme is prone to massive fraud. And I suppose that solving the fraud problem is a neccessary step in realizing this vision.
But I honestly believe we are headed in a direction where all the existing models get flipped and the power of the open internet gets harnessed in ways that we are just beginning to imagine.
So into this emerging/brewing ideaspace steps my friend Mark Pincus who is always at least one step ahead of me. He takes it one further and says this flipped/open model is going to work for social networks too. And he should know since he runs one of the largest social networks, called Tribe.net.
The PeopleWeb will open up the closed walls of the existing social networks and turn the web into one big one. Mark's got it right. Go read his whole rant on the subject.