All smartphones suck a huge amount of juice. Trick is to use them wisely. Turn the screen brightness down, turn off wifi when not in use, turn off bluetooth when not in use, use the gps sparingly. Texting is the preferred method of communication over phone calls and then via gtalk rather than SMS because you DO have all your google services enabled right?
Charge your device overnight preferably with the device off. If you use your device as your alarm clock to wake you up, then charge it overnight anyways, then when you wake up turn off the phone and let it charge another 20-30 mins or so as you get ready to leave in the morning. That allows the device to fully top off while not drawing any other current from the charger. That procedure alone works wonders, and really is the smartest way to charge any device.
Of course if you use it in yer vehicle as a GPS and/or stream your tunes there is no reason not to have it plugged in to a car charger.
I do not like the extended batteries that require a modified hump to the battery cover. It messes with the sleek aesthetics of the device and the significant investment I have in its other accessories like its armor car holder. Seidio has a 1850mah extended battery that fits in the standard battery compartment of the Incredible. They also have an external charger that plugs directly into a wall socket.
My battery runs me approx 16/hrs day under moderate use. If I use the gps or play a lot of games or such of course it dies quick. But between the car charger, the extended battery, the stock battery, the wall charger and the stock charger, I am never without juice.
Sounds like a lot, but its less than a hunnerd bucks worth of gear.