Forget film rentals, the next big thing for college students is going to be book rentals, at least if Amazon’s U.S. arm has anything to do with it, the AFP reports. The online retailer claims savings of up to 70% and, at the end of the rental period (a 130 day semester), the books are returned for free by means of a pre-paid address label. Naturally, e-books are also eligible for rental, at a slightly lower cost…