The Net Book of Feats has the Extra Domain feat. It isn't overpowered, not that much at all. First, your God has to have that Domain (you choose from the remaining ones for your God), so in my home game, my Cleric of Mayaheine with Good and War domains, has the choice to add either Law or Protection. Whoopty-do. Those domain powers and most of the spells suck. I see it in most gods the same way, until you get into the FRCS, but then again, that whole book is made to be powerful, so what's the problem? Why is everyone always trying to limit their players?