Google Book Search is a Google project that aims to make the world's books searchable, similar to the web. It allows one to search the full text of a book. Google Book Search allows one to search out-of-copyright books or books that they have an agreement with publishers for. Along with such an immense project come many issues. Google is in the process of trying to get publishers to join Google Book Search. Google Book Search is continually updated.
Recent updates mention in their Official Blog as of November 21st, 2006 include a variety of things. One of which is the ability to zoom in on text and images. Now you can zoom in or out using the magnifying tool. Another update is the ability to look at the whole book, page under page on a single webpage. This means no more reloads when you turn to another page. You can either have one page below each other like a scroll or have two-page mode with pages side by side then another set of pages side by side underneath. Another update is the ability to use your mouse wheel to scroll or you can drag with the mouse or hit the spacebar to jump to the next page.
Now you can find other related books to the one your reading that may be of interest by clicking the "About this book" link. Once you click, it will display a list of similar books to the one you are reading. This sounds similar to the Amazon "Other Customers Bought..." feature. Lastly, one can find other books of interest by looking at the citations or references. By clicking a citation or reference one can view the other book if it is available on Google Book Search.
These sound like some pretty nice updates and they will most likely continue with the growth of the Google service.
http://googleblog.blogspot.com/2006/11/new-way-to-browse-books.html