In my opinion, the coolest new feature is one called “popular passages.” This feature does two very useful things. First, it cross-indexes and links books to relevant subject matter. So, when you run across a quote from Plato in the course of the reading, once click will take you straight to the relevant passage in The Republic. What may be even cooler, though, is that it tells readers how often and in what books a certain passage or quotation has occurred. Thus, one can, if so inclined, trace the intellectual heritage of an idea, or even a specific quote through the many books maintained in Google’s library.
Other features include the ability to create and share personal libraries and to take direct quotes from public domain books and add them to web paged and blogs. All in all, good stuff that any avid reader (and commentator) should find handy.