Exponentially? Not that I'm aware of. I've seen examples of highly focused niche sites that have generated nontrivial (and growing) ad revenue, but so far nothing viral. And really this touches on one of the key problems in the newspaper world today: editors who are looking for the next Big Thing to replace the classifieds cash cow. I believe tremendous resources are being squandered on what is basically a waste of time. If there was one overarching business model that was going to "save" newspapers, someone would have struck on it by now and everyone would be following suit. The future (again if one exists) is in many carefully managed small revenue streams.