please see this site http://www.crazyideas.com it has only ads ( provided by google ) which you can see when you hover your mouse of these ads but these ads are not displaying the message "Ads by Gooogle" and the owner doesnt seem to be a premium publisher. as he doesn't have any content at all on this page
Very good question. Here is a more direct link: http://apps5.oingo.com/apps/domainpark/domainpark.cgi?client=TWOS3769&s=crazyideas.com
Its a parked domian - the company at Oingo.com is a Premium publisher that has thousands of parked domains and enough traffic to get those unique ads. The irony is that Google should be trying to dump such 'pointless' sites from its indexes. Also look at sedo.com, Godaddy.com etc who offer similar services for such parked domains. http://www.google.com/domainpark/ for more detail - I didn't realise that Google did this themselves.