Buying ads just for the pagerank
Tim O’Reilly discovered that a number of advertisers are buying ads on his sites (and others with high pagerank) not because they want clickthroughs, but because the pagerank boost is cheaper than buying their keywords through AdWords.
The discussion about whether there’s anything wrong with this is pretty interesting:
http://radar.oreilly.com/archives/2005/08/search_engine_s_2.html
