If you're a high-flying type rocking two contracts and, ultimately, two SIM cards, the new 3-in-1 External Battery over at USBFever could save you a lot of hot-swapping -- assuming at least one of those SIM cards is currently in an iPhone 3G or 3GS. It looks like an ordinary, bulky external battery, but inside packs room for a second SIM. Swapping is handled via an on-phone application and, according to the online instructions, it'll take about two minutes for your handset to figure out exactly what the heck is going on and reconnect to the different network. Sadly the phone can't monitor both cards simultaneously, so if you fre
