Hello, names Branson Maddocks
Not that I am suggesting that this be the project...but It would be nice to have a DM friendly book for building authentic pantheons, and religions into their Campaign Setting, without feeling the need to rely on the D&D classics which often come across as being uncreative or dusty from time (sorry Mr. Moore).
Such a book could deal with how to handle
Divine Magic Sources: I.E. From faith, supplied by the god/gods
Monothesistic vs. Polytheisistic cultures
Heresy, in all its forms (unpeity, etc.)
While the book could be System independant, it could just as easily be System dependant (3.5e
4e whichever)