Navigating Wikipedia has grown substantially more complex  and rigorous  since I last made additions some years ago, so I will just post this link here, and if anyone sees fit they may want to add it to the references. It is an (approximately) 30-page article entitled "Search Engine Optimization and User Behavior" scheduled for inclusion in the 2009 Encyclopedia of Library and Information Sciences. 

 http://www.hastingsresearch.com/net/09-SEO-ELIS-encyclopedia-article.html 
 (The material itself does NOT come under the GFDL.) 

 Hastings Research never did much SEO work, and no longer advertises the service; we are not SEO consultants.