I was lucky enough to get a preview of this wonderful little guide in its infancy, and it has helped me so much. Mind you, there are guides for DIY ebook formatting all over the web, but often they seem to suppose the following: (1) you have at least some HTML skills. (2) You don't have to be guided step-by-step, you just need a breezy overview. (3) You don't use Word. I can't tell you how many other guides I tried to follow, step by step, only to still end up with weird indents, inexplicable blank pages, etc. And when I asked for help, the answer was, "Oh, you shouldn't use Word. Or a PC." Not exactly helpful.
So with this guide, if you actually use Word on a PC, you can follow the steps and format your own book. And reformat it every time you catch a typo, decide to alter the back matter, etc.