Amazon has been renting out Kindle editions of textbooks for sometime now, but not all the educational tomes you need may be available in electronic form. And, believe it or not, some people just plain prefer paper to E-ink -- especially since its much easier to take notes in the margins. Now many of the more expensive texts on the site also feature a rent option. Most are in the $30 to $60 range and are rented by the semester, which Amazon counts as 130 days. Should you need it for a bit longer, you can extend your rental period by 15 days, but only once. On the plu
