Running out of battery life in the middle of that important call? FastMac iV to the rescue. This second-generation, 3100 mAH external battery pack gives your iPhone 3G up to 24 hours of talk time, 750 hours (31 days) of standby, 20+ hours of video and almost 72 hours of audio playback time (depending on your settings). At the very least, it'll double — maybe even treble — your iPhone-ing between charges.
It's not the first or only battery pack on the market (there's also Mophie's Juice Pack), but the iV's added touches like a built-in LED flash/flashlight and a second USB port to charge additional gadgets– plus, at US$80.00, a lower price tag — might serve to (pardon the pun) lower your resistance to buying one.
[More info at FastMac's web site]