WordPress eBook Creator gives you custom controls to automatically or manually create Mobipocket .mobi or .epub files for use on a wide variety of ebook readers.
Free eBook Creator WordPress Plugin can create eReader files from any RSS/Atom feed or from your blogs database. It can be setup to generate new eReader files every day, every week, every month, or every time your blog is updated..
All of these files can be seen, managed, and downloaded through WordPress’s built in Media Library.
A handy widget has been provided for announcing your eBook capabilities to your readers.