Amazon quietly introduces Kindle rentals for US readers, bases prices on duration

Think you can finish a 168-page novel in a month? It might pay to opt for Amazon's new Kindle rental feature, now available on an incredibly limited number of titles. A few options published by Princeton University Press appear to represent the site's introductory offering. The 5 Elements of Effective Thinking isn't exactly a bestseller -- we weren't able to locate any eligible books from that list -- but it's a popular enough title, with a current rank of 1,432 (if the rental option takes off, ...