Monoprice.com (source of dirt cheap cables – seriously, don’t pay full price for cables. I have no affiliation with them, other than a happy customer) has had a $15 external 2200mAh iPhone/iPod battery for a while now. I’ve seen it, and kind of steered clear of it, because I was uncertain of the quality. But then I saw a couple of reviews (at TUAW and Minimal Mac) that were happy with it, so I took the plunge. I also picked up two iPod cables, two USB AC adapters, and 2 12V car USB adapters in the same order. The total price was about $23.The stuff arrived last week, just before the long Thanksgiving weekend, and I had a chance to use the battery pretty extensively, as I spent many an hour at my mother in law’s house playing games and doing other battery draining things on my iPhone 3GS. So what’s the verdict? This thing is the best $15 you can spend if you own an iPhone. Period. The battery capacity is 2200mAh, which is about twice the iPhone’s internal capacity, so you can charge it up (about) twice. You can also attach the battery and charge and use at the same time. The connection is the standard iPod/iPhone connector, so it will work with any device or charger that has one. It’s made of glossy, smooth plastic, sort of like the back of the iPhone 3G/3GS (though it’s thicker). There are tons of other external battery options out there – the Mophie Juice Pack Air is a popular one, at 1200 mAh and $79. But this little cheapie from Monoprice has almost twice the battery capacity at less than a quarter of the price. Most of the time, I find myself in easy reach of a charging source for my iPhone (my desk, the car, etc.), but for the times when I’m not, this little guy is definitely coming with me in my bag or in a pocket. It’ll be a lifesaver for conferences, travel, and other all day events. If you have an iPhone/iPod, and have ever wished your battery would last just a little bit longer, or are sick of carrying around a charging plug and cable all the time, just to keep your phone running, you should DEFINITELY get one of these. Highly recommended.