The Burning Slug book engine (http://burningslug.com/) is quite possibly the fastest way to get your text into book form. From the same manuscript file you can produce:
* EPUB format (iBooks, the Barnes & Noble Nook, and many other readers)
* MOBI format (Kindle)
* Print-ready PDF
* Stand-alone website
This manual was itself compiled with Burning Slug. The EPUB, Kindle, and print versions were all generated from the same manuscript without any text changes for the different versions.