Amazon.com is now offering textbook rentals for college students. The web-based retailer already is offering a free six-month trial of its Amazon Prime two-day shipping program and a bonus $5 MP3 credit for purchasing at least $25 worth of textbooks through its site. Go HERE for all of these offers. Note: Amazon also has a program that offers college students gift cards in exchange for their used textbooks. Go HERE for details of that program.