As glued to the net as we all are, there's vast quantities of content that is not available online.
Hack let you convert encrypted Mobipocket files that were intended for another reader so that that work on Kindle.
Non DRM Mobipocket format is already supported on the Kindle - just drag and drop.
Plenty of free e-books in Mobipocket format show up fine on Kindle.
A revolutionary portable reader that wirelessly downloads books, newspapers, magazines and blogs to a crisp, high-resolution electronic paper display that looks and reads like real paper, even in bright sunlight.