Website: www.chegg.com 

Labeled as the Netflix of textbooks, Chegg lets students rent schoolbooks for an entire semester, quarter, or up to 60 days, while providing a prepaid UPS label to ship them back. Rentals range anywhere between 30-80 percent off the original price, with a majority falling around the 50 percent bracket. There is a 30-day “any reason” return policy and free return shipping, too. iPhone owners also have the privilege of renting and viewing textbooks on their handset with the Chegg smartphone app. On top of that, the company is working closely with the American Forests' Global ReLead campaign to prevent deforestation: planting one tree for every rented book. Sweet.