isbn.nu is a web site that provides price comparisons among over a dozen online stores that are either booksellers, auction sites, used book dealer networks, or a combination of two or three. They retrieve prices that as timely as each bookselling site allows and display them in order of lowest available price to highest price. In addition you can also display results based on timelyness of delivery. This site is a good example of a Web 2.0 tool that takes advantage of the methods that book sellers provide to allow customers easy access to their products. The next time you are looking for a book, rather than visit each book sellers individual site, give isbn.nu a try.