Chegg is a well-positioned textbook rental service that lets students rent as many textbooks as they like. Textbook rentals save a lot of money compared to buying the same books new. The textbook rental service offered by Chegg also allows users to buy and sell books through a single, easy-to-use interface.

As a successful and profitable business, Chegg's textbook rental service reduces the need to print new textbooks so it saves trees. Chegg also plants a tree for each book it rents -- over 1.5 million to date. Sounds like a win for students, a win for Chegg and a win for the environment, too.