How to change page layout for newbie vs superfan visitors?

I recently read this article on distinguishing between one-time visitor "noobs" vs regular visitor "superfans", to dish up a different page to each.
http://fortuito.us/2007/05/how_ads_really_work_superfans_1

Specifically, the idea is to show ads to the noobs (who are probably visiting via search engine, and may very well be looking for content in your ads), and not show ads to the superfans who are their for your content and are only annoyed by ads.

I like the idea. In Drupal, the obvious idea would be to show AdSense blocks to the noobs and not to the superfans. If you expect your superfans to be registered users, it should be easy: just don't show ad blocks to the registered user roles. The Persistent Login module looks like it'd help ensure that those registered users actually do log in (though I haven't yet tried the module).

But how about a site for which you don't necessarily expect your best fans to log in regularly, or even be registered users? For example, I have sites with regular, valued visitors who participate in discussions, but for whatever reason don't wish to deal with registration and login. What would be a good way to reduce ads shown to these users?

The article above suggests cookies to track number of visits in a given time period, identifying the superfans. Is there an existing Drupal tool for doing this, or achieving the same effect?