I've had pretty bad battery life on my Evo 4G. I figured I just had to live with it but I was starting to think it was just too bad to be normal. Well I don't know if the app just works that well, or there was another app/service seriously draining my battery but after installing "JuiceDefender Beta" my battery hasn't dropped down to half a battery since last night and this morning I browsed the web a bit took some pictures with Vignette testing things out.. launched some other apps.. texted etc.. Well normally if I don't plug in my Evo before I go to sleep I wake up to at least half a battery and it very rapidly dies from there. I feel like I got 8 hours of moderate usage before I felt like the battery was too close to dying to not charge it up. I suspect it was an idle battery usage problem but I'm really excited for my battery lasting now. Try it out if you're getting very bad battery life. I have JuiceDefender Beta on the normal settings, I don't even really see it turning anything off or notice any performance changes or it taking any longer to use data or anything.