Amazon can do a lot of money only from selling kindle, like Apple does with the iPod.
There are converters available from Amazon and/or Mobi for pdf and doc files.
Non DRM Mobipocket format is already supported on the Kindle - just drag and drop.
DRM refers to the fact that you can't view Amazon Kindle books on other devices (including your computer), or on other Kindles - i.e. no sharing, the purpose of DRM.
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.