Google recently announced two new enhancement to Google Books. You can now browse through many of the Google Books categories using a horizontally scrolling interface. This same horizontally scrolling interface is also applied to the collections of books that you build within your Google Books account. Now you can create your own public and private “bookshelves” in your Google Books account.
http://www.freetech4teachers.com/2010/01/google-books-adds-book-shelving-options.html