Plenty of free e-books in Mobipocket format show up fine on Kindle.
There are converters available from Amazon and/or Mobi for pdf and doc files.
Use Mobipocket software to convert PDFs to that format so you can read them on Kindle.
The hack allow ENCRYPTED Mobi files to be read on the Kindle. So you can buy a DRM-protected mobi book and read it 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.