Integral Real Time Clock version of ATmega328P or ATmega2560?? By anyone?

Does anyone know if there is a ATmega328P or ATmega2560 development board that includes a DS1307, etc. real time clock & on-board battery?

I have seen one kit somewhere, but it was no longer available.

Am I the only one that would love this product?

Battery holder on the bottom.
Maybe I should have some more made up.