westfw:
It seems like a job for a microcontroller to me. How about an ATtiny4 that's under $0.50 in q100 ? (PIC 10F and Freescale RS08 are also available in that price range.)
An ATtiny4 would certainly work, although you are exactly right that avoiding writing/testing/maintaining firmware is exactly what I'm after here... especially since it's primary purpose is to bail me out in case of firmware problems. That could be a really excellent project to start in the community though replicating this functionality on an ATtiny4. I have a feeling it would get used a lot for a lot of battery powered Arduino projects. I'd use it in a heartbeat and contribute if it were already built and tested! 