I use trend micro longevity beta app - has a handy setting of "just a phone mode" which effectively turns the lot off other than 2g for calls and text. Also has alerts for
- Apps that hog power
- fully charged alert
- fast drain alert
- low power alert
Its optimise function can be set to maximise battery life by turning off apps running that aren't being used and its "power hogs" screen shows clearer detail of each apps battery usage than the HTC supplied one. It has a clear battery status screen which can show either time left of battery or the % of power left. Also converts to how much time to fully charged when charging.
Using this app and the widgets for screen rightness, 3G , WiFi for toggling them on or off dependent on need means I get a good 24 -36hr of battery life per charge. I use the 1800 mAh Andida Li-ION battery which a few of us bought last year. I tend to leave the phone charging over night when needing a top-up