Google Books (Mobile)
Book Search works just like web search. Try a search on Google Books or on Google.com. When they find a book with content that contains a match for your search terms, they'll link to it in your search results. If the book is out of copyright, or the publisher has given them permission, you'll be able to see a preview of the book, and in some cases the entire text. If it's in the public domain, you're free to download a PDF copy. They've created reference pages for every book so you can quickly find all kinds of relevant information: book reviews, web references, maps and more. See an example. If you find a book you like, click on the "Buy this book" and "Borrow this book" links to see where you can buy or borrow it.