The Google Books site allows registered users to organize their book collections online, categorizing books according to those identified as favorites, books already read, and books in the reading queue. You can access a particular user's collection using the Zend_Gdata component by prompting the user to log in to his or her Google account. When the user has successfully authenticated, you can retrieve information about his or her collection, including a list of titles, much as you did in the previous example:
Executing this snippet retrieves the 12 books in my collection, producing the output partially represented in Figure 2. Of course, in a real-world situation, you would prompt the user to provide his authentication information via a web form.
The powerful Zend_Gdata_Books class provides a convenient solution for not only accessing Google's vast literary database, but also for actually participating in the service's community by allowing users to manage their book collections in new and unique ways. If you build anything new using this feature, tell us about it in the comments!