I just posted these links in a thread, but thought they might be useful to all who crave longer battery.
They won't necessarily make your phone look any better, though the second one isn't too bad; I know someone with one, it raises the camera end of the phone well off the ground helping to protect it, while the other battery has a kick stand!
Odds And Pods-HTC Desire Extended 2600mAh Battery and Replacement Back Cover
HTC HD2 BP E400 Extended Battery (2300mAh) + Cover (with Kickstand) from Clove Technology
They won't necessarily make your phone look any better, though the second one isn't too bad; I know someone with one, it raises the camera end of the phone well off the ground helping to protect it, while the other battery has a kick stand!
Odds And Pods-HTC Desire Extended 2600mAh Battery and Replacement Back Cover
HTC HD2 BP E400 Extended Battery (2300mAh) + Cover (with Kickstand) from Clove Technology