I'm writing documentation for a WordPress template I've made. I'd like to be able to provide documentation in HTML, PDF, ePub and Mobi formats without having to spend any time tweaking each format other than the one I write it in as i'll probably need to update it often. I assume it is easiest to write it in HTML but perhaps a word doc to all four might be best. Is there an app that outputs in all of these formats?
Take a look at Calibre. You can use it for the conversion part.