Kindle reader software is FREE and available for the PC, Mac, iPhone/iPad/iPod Touch, Android and Windows Phone.
Amazon.com (Kindle), Apple (iBooks) and Barnes and Noble (Nook) have extensive book libraries of new releases as well as classics. You would not be disappointed with any of these 3 e-Readers.
Kindle is one of my Top 10 Most Useful Apps. Click Here to read about the others.