There are several 3rd party battery metering apps which can draw graph based on battery reading, but if you have recently updated your HTC smartphone to Android 2.3.3 (Gingerbread), your phone actually has a pretty nice built-in battery reading graph within the system. This feature is found in Gingerbread version of HTC Incredible S, HTC Desire HD, etc.
Go to Settings > About phone >Battery > Battery use and you'll see the screen similar to as below.
Note that on top of the screen is a slanting slope with information telling you how much time your phone is on battery since last charged. In fact, that slanting slope is your phone's battery reading graph. Right below the graph you will be able to see some blue marks. Don't worry, they are not screen display problem, but are actually indicators when battery is used by phone activities. If you charged your phone, you will also see green bar plotting the battery charging period.
Tap on it and you will get a clearer graph. The blue battery usage marks are further break down to the respective activity.
If you turn your phone to landscape orientation, this screen will also adjust itself to landscape view.
I think, with this nice battery plotting feature, you don't need to use any 3rd party battery metering apps anymore.