I'm not causing so much of a draw that it kills the battery before it's next recharge.
The simplest approach to reduce current consumption would be to put a mcu into sleep / idle.
The benefits of sleeping, however, maybe offset by frequent waking up. In that case, think of using a rc filter and a few mcu pins to dynamically throttle the clock speed.
That's also not a bad idea.
I'm going to try one of two things:
1 - build a barebones board powered off of an LM7805. My input voltage is +12V so the quiescent current should be about 6mA. Along with the barebones board running at about 15-20mA I should be able to keep the overall current under 30mA. Once the power source turns on and the mains is running off of a charger instead of the battery the current draw is an "unnecessary worry."
2 - Power up the arduino dependant on an external signal. Once on, a pulse-timer relay will energize providing power to the arduino along with the main power source (diode isolating the two from each other). Once the external signal goes away, the pulse-timer relay will keep the Arduino powered for a set time allowing it to finish out it's program and then fully shut down. At this point the process starts over again.
fyi - My 'power source' is a car, hence the 12V application and concern about current draw.