I liked this article from late January 2013 in the NY Times by Corey Kilgannon. It discusses the circulation of an American Girl doll, named Kristen, in the New York Public Library system. According to the article the demand to borrow Kristen is quite high.
This article may be of interest to children’s librarians out there.
An update to the story is available from the link cited below.
http://cityroom.blogs.nytimes.com/2013/01/29/at-a-library-an-outpouring-of-support-and-new-dolls/