There are converters available from Amazon and/or Mobi for pdf and doc files.
Granted the PDF converter seems to have some trouble with graphics PDF's, but for books the converter works very well.
As glued to the net as we all are, there's vast quantities of content that is not available online.
The Kindle supports Mobipocket files directly. You don't need to write a script to do that.
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.