The December/January issue of Fast Company magazine has a one-page feature on Aayush Phumbhra's Chegg, a textbook rental business.
Here are some of the stats from the article:
4 million titles available
$30 rental on a book that you would by for $100 new or $75 used
7,000 campuses have students who use Chegg.com
8 campus bookstores work directly with Chegg
100 campus bookstores are interested in working directly with Chegg