Regular readers will know that I follow the Hitwise blog. I was interested to see their note on Google Book Search the other day, prompted by the settlement which discussed which sites benefited from downstream traffic from that site. In other words, where do people go when they leave Google Book Search by following links.
Among other things, the settlement allows universities and libraries to buy a subscription to the entire collection of scanned books in Google's archives. Last week, 22% of visits from Google Book Search went to an Education website, with Worldcat (a website that allows users to search library catalogs) the #3 downstream website overall and the #1 Education website. [Hitwise Intelligence - Heather Hopkins - US: Google Books Drives Visits to Book Retailers]
If I am reading the entry correctly, the order of downstream destinations is  Google.com,  Amazon.com, and  Worldcat.org.