Hacker Igor Skochinsky used DRM to load Mobipocket books onto his Kindle. Using a series of scripts, he's able to convert eBook files to Amazon's AZW format and then add the necessary serial number DRM, specialized per an individual's particular Kindle.
Kindles can read a variety of non-proprietary, non-DRM'ed formats. They read TXT, HTML, JPEG, and non-DRM Mobi files directly.
Use Mobipocket software to convert PDFs to that format so you can read them on Kindle.
The Kindle has many flaws, but it does allow you to read a few different non-DRM formats.
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.