CJ’s tutorials seem a bit technological at first, if you aren’t familiar with formatting, but stick with it, and eventually it all comes together.
Smashwords Style Guide This free resource is the Bible as far as getting your book distributed through Smashwords is concerned. With it you can create a clean, simple book.
Mobipocket Fast, free, easy app for converting your files to .mobi, the files used by Kindle.
Calibre Another fast, easy, and free program. This converts from a huge number of formats to a huge number of formats.