Uninstall whatever battery app you're using and install Battery Left. I've used a total of 3 battery apps so far. And Battery Left has them beat. It tells you how much time is left on your Droid. Of course it has to calibrate itself, and the longer it calibrates, the more accurate it gets. Right now, I'm at 62% accurate. And it shows I have 15:59 hours left after I immediately took it off the charger.
I'm anxious to see how much time my Droid can really last when its closer to 100% accuracy.
Download it, and see for yourself.