I would like to know if it could be possible to use adb (Android Debug Bridge) to tell the phone to lower its CPU max freq.
I'd like to use less battery if possible, and in my use case I don't mind if some tasks are a little slower.
There is a program called SetCPU which will allow you to over/under clock the processor. The advantage here is the ability to set profiles to have the phone determine when to adjust the processor, such as when the phone is at a certain temprature, or if it's plugged in or not.
I've been using it on my Droid Eris for a while now, and the results have been great.