If you're experiencing short battery life on your HTC EVO, chances are you've tried downloading apps to kill processes, shut things off, and see what's using the phone's juice. There are applications out there that can show you all sorts of info about other programs as long as they're running, but that means they're using battery to show you what's using battery.
One of the best indicators we have of how much power is being drained by apps is by how much they use the CPU. There are other factors to figuring out drain too, such as how much data they transmit over the air, how much screen time they have, whether they use the camera or not, and so on but we're just looking at CPU times today.
If you're on an EVO 3D with a stock dialer, you can dial #*#*INFO#*#* to pull up a usage statistics system menu that includes phone and battery information, as well as WiFi and CPU usage. It will show you what's been eating your CPU time since you booted. The higher the usage, you can assume the higher the battery use.
It's useful, built into the OS, and doesn't require any additional apps that may be pulling ads off the internet and draining your battery to display commercials for company X. It also will show statistics for programs that are not shown in Menu->Settings->About->Battery->Battery use.
The same menu exists on the EVO 4G; however, the only way I have found to enter it is via an app called Battery Monitor Widget. There's a "tests" button there that drops you into this menu. If anyone has the dialer code to get in, please let me know.
This isn't going to solve all aspects of a quickly draining battery, of course, but it might help you locate an errant application that's tapping your battery like a Capri Sun. Oh, and it's free.