Hi, hope this is the right area for this thread. I have written books and done some translation work on the New Testament and related topics. I have them in two separate websites, both running on my own php scripts:
The Gift New Testament
Books of a Fether
The downloads were made with php code I wrote which extracts the chapters from the database and writes them in both .tex and .xhtml format. I download these and then run a Linux "bash" script that creates ePub and PDF files. The PDFs are in two forms: 5-1/2x8-1/2 to read as-is, and an imposed version for printing on any duplex printer.
The advantage of course is that the text of the books is only written in one form, so any changes can be made in the database and then the reader/PDF versions are easily made with a few clicks of the mouse. The difficulty was in writing the software and cleaning up the original text for ease of conversion.
I'd be happy to share info with anyone interested in doing something like this. The software is only as modular as I needed it to be for my own books, but it could certainly be adapted for more modular use.