The Kindle Personal Document service can convert and deliver the following types of documents:
Microsoft Word (.doc)
Rich Text Format (.rtf)
HTML (.htm, .html)
Text (.txt) documents
Archived documents (zip , x-zip) and compressed archived documents
Mobi book
Images that are of type JPEGs (*.jpg), GIFs (*.gif), Bitmaps (*.bmp), and PNG images (*.png).
Adobe PDF (.pdf) documents are delivered without conversion to the Kindle DX, the second generation and the latest generation Kindle devices.
The following document types are converted and delivered on an experimental basis:
Microsoft Word 11 (.docx)
Adobe PDF (.pdf) for First Generation Kindles