conversion of Kindle format

Kindle have its own document format, .azw. Right now Amazon supports the conversion from .doc, .txt, .rtf... editable text format. You can send your file to @kindle.com. Then Amazon would send directly to your kindle via wireless 3G for a fee. Or send you the download link of converted file via your computer USB port for free. Then you download it to the kindle's "documents" folder. You can simply send the file to @free.kindle.com, then Amazon would give your the download link for free, you can download it to your kindle's "documents" folder.