Sure. PDFs are natively supported in Kindle 2's and DXes. You can convert PDF's to a supported format for older Kindles. Also, you can sell .mobi files and they

Sure. PDFs are natively supported in Kindle 2's and DXes. You can convert PDF's to a supported format for older Kindles. Also, you can sell .mobi files and they work just fine on any Kindle. Once you have a file, you can put it on the Kindle over USB for free or you can send it to an email address Amazon gives you for file transfer (15 cents per some amount of file size...I forget how much). The Kindle store uses DRM, but the Kindle certainly doesn't require it on the files it will let you read. It's like an iPod in the pre-iTunes Plus era.