Google Book Downloader is a free tool for non commercial purpose which allows you to find Books availble in Google Books site and then download the book along with available pages in PDF format. All you need is to get the Book Code which acts as key to search it. This key can be retrieved from the Google Books site.
This tools is still in Alpha @ Codeplex running under this project.
This is an excellent tool if you are intrested only at vertain pages and not the whole book and if there is any book availble on Google Books, just hit download and it will saved as PDF just for you. Give Google Book Downloader a try