I'm sure many people know this already but I just experienced it. I'm currently on vacation in puerto rico and there is Extended Service (Voice & txt) but only 1x Data and its barely worth it. So I've turned of my Eris' Mobile Network to conserve Battery... And BOY does it! I've had my Eris on for two days now and my battery is at 71%! I never thought I'd see this lol. The funny thing is I have Wifi and GPS switched on! Seems like these two don't use the battery as much as the 3G connection. Anyways, back to the beach!