I use Locale to manage my phone based on a few criteria
For calendar events - I have the screen brightness turned down, the screen timeout to 15 seconds, the ringer on silent with vibrate, WiFi, BT, and GPS turned off.
On battery power I have the screen brightness up, and the screen timeout at 2 minutes.
Seems to get my battery from 6am to at least 8pm with one, maybe two phonecalls and some light usage.