[wodin]

I have an HTC EVO 4G, and after the last firmware upgrade the battery life was abysmal. Two to four hours of moderate use. Whilst looking for a solution, I ran across an app called "Green Power" which works by switching off the radios while the screen is off, and then turning them on for short intervals to check for email/sync requirements/etc.

This thing is phenomenal! My EVO now lasts all day w/o going below 50%. I have no affiliation with the developers, other than being a satisfied customer. Check it out, there is a free version and a paid (~$1 USD). I happily paid for the paid version, and if there wasn't a paid version would gladly make a donation to the dev.