Drop the Power control widget on one of your home screens.
Disable WIFI and GPS when you are not using them.
I only pop on WIFI when I'm near a known network. I pop it off when I'm done browsing or whatever. I turn on GPS only when exact location is required for nav, skymap, near me now, etc.
This practice will save you some battery juice. Turn them off when your done. 3G is very efficient.
When you first set up the phone it asks you if you want GPS on or off, if you turned it on it could be burning through your battery searching for satellites. I only enabled network location at all times.
If your in a poor reception area (no 3G, or low bars) it could burn through your battery trying to maintain good connection to a tower.
An app you recently installed might be chewing through the power also.
Check Battery Use in Settings/About phone.
Bluetooth usually only eats juice when its actually paired to a device and that device is in use, otherwise it sleeps and uses hardly any power in a non-paired or non-active state. If you don't use it, disable it of course.
Use the Auto brightness setting in Display. It's more efficient.
If none of the above things give you some more battery life, maybe it really is a bad battery/phone.
-droidosis-