Shop4Tech has the Solar Battery Charger for iPhones, iPods, and USB Devices for $16 - 15% off with coupon code ALL15 [Exp 9/16] = $14 with free shipping. Features a Li-ion polymer battery with 1350 mAH capacity and two power output ports (one for iPhone/iPod, one USB). Includes USB cable.
That's 8 hours of GOOD sunlight, you won't get that in a single day in the woods. The purpose would be if you are, as suggested, out in the woods for long periods and just need to keep enough of a charge that if there were an emergency you had enough juice to make a quick call.
However, I would suggest a decent quality (not the $5 specials from Hong Kong) hand-crank generator instead, instead of waiting a half hour or more you can generate enough in a couple minutes, PLUS some devices seem to need a certain minimum current rate at 5V to charge at all, meaning a direct sun-charge isn't possible, instead you would need to leave this out charging the battery pack quite a bit then come back later and at that point attach it to the phone/etc to charge it.
Takes nearly 8 hours for a complete charge. Short of being stuck in the woods, I'm not certain the practicallity of this
That's 8 hours of GOOD sunlight, you won't get that in a single day in the woods. The purpose would be if you are, as suggested, out in the woods for long periods and just need to keep enough of a charge that if there were an emergency you had enough juice to make a quick call.
However, I would suggest a decent quality (not the $5 specials from Hong Kong) hand-crank generator instead, instead of waiting a half hour or more you can generate enough in a couple minutes, PLUS some devices seem to need a certain minimum current rate at 5V to charge at all, meaning a direct sun-charge isn't possible, instead you would need to leave this out charging the battery pack quite a bit then come back later and at that point attach it to the phone/etc to charge it.