If you want to increase the lifetime, use Battery Status software and activate CPU Scaler, it's great!
Before: I used only 201Mhz freq, my battery had a lifetime of 1 day using it normally.
Now: I've overclocked it to 260Mhz with CPU Scaler activated (low: 99Mhz, average: 201, max: 260) and my touch can stay 3 days without charge need.
I still use these settings but I have a unlimited data contract with my operator, so my touch is connected all the time to Edge (push mail and weather updates), and with these settings I have to charge it every day. Don't care about this since I work with a PC all the time.
I think if I used all the time the original freq, I'd have to charge it more often...
Samsung Galaxy Note
Locked in an Asylum
HTC HD2 EU