I recently rooted my 16-month-old Eris and installed the XTRSense 5.01 ROM. Among my many goals was to extend the battery life. All of my other goals were attained and then some, but not that one. Then I browsed through the posts on the Thunderbolt and, as expected, found a long thread on battery life. One suggestion there struck me as being revolutionary, yet brain-dead simple. When you don't need a data connection, use a toggle to turn it off. Your Eris will send and receive phone calls and texts with both 3G and Wi-Fi turned off. When your phone is in your pocket, turn 3G and Wi-Fi off. When you want to use your phone for anything other than calls and texts, simply use the toggle to turn 3G back on. Within just a few (maybe 15) seconds, all of your email accounts will update, your weather will update, etc. This simple technique should add several hours to your daily battery life, without any sacrifice on your part. I wish I had thought of this a long time ago!