Libraries using the Overdrive content delivery system for patrons to checkout books are experiencing record numbers across the USA. Since 2007, the company has loaned out almost 60 million ebooks and in 2011 they have just reached the 26 million mark.
Overdrive currently reaches over 17,000 libraries in the USA and K12 schools. It is really the best stocked content distribution system for many of the most popular e-readers. A few months ago they implemented Kindle lending, so people using the seminal Amazon e-reader line of devices are not longer left out. Most of the success of Overdrive comes from ebooks, but audiobooks continue to gain in popularity.
Users can basically check out a book for up to 14 days and all they need to get started is a library to support it and a library card. You can then sign into the service and start borrowing! There are wait-lists for popular books and many people use the service in order to continue to fiendishly read, but spend less.