FindBooksFast is simply the fastest book search engine for the iPhone. Start typing a book’s title or author’s name and search results appear instantly as you are typing. There’s no need to type the full title or author’s name because search results begin to appear after the first two characters are entered and results are further refined as you type each additional character. A full search is executed automatically after each keystroke! FindBooksFast returns 2-5 search results per second (speed will vary depending on whether you are connected via wifi, 3G or Edge.)

http://appshopper.com/lifestyle/findbooksfast