Chegg.com is pioneering a Netflix-inspired college textbook rental service. I have been out of college for a while, but even back then textbooks were expensive.
Originally modeling itself around a Craigslist-type service where students could sell all manner of items as the school year started or finished, this business model did not take off. Chegg's founders realized, however, that textbooks were one item that students used the site to buy and sell.
It will be interesting to see if Amazon's large-format Kindle DX, which is being seeded to a number of universities this fall, will supplant the need for paper textbooks. However, Chegg, whose name derives from the Chicken or Egg puzzle, seems to have established a niche for itself.