San Francisco-based Better World Books looks a bit like a philanthropic mission: The company saves old textbooks from the landfills, selling them cheaply through its online store and buying carbon credits to offset emissions from shipping. However, Better World is a for-profit venture, and earned over $16 million in revenue last year. The company says it has also saved 6,500 tons of books from going to landfills and bought 2,400 tons of carbon offsets.