I just bought a Powerfilm AA/USB solar charger. It charges 2 batteries at one time. Folds up to a nice small package, seems durable enough. With the correct cable it can be used to charge any number of USB appliances.

Got it at REI with my dividend and the annual 20% discount coupon.

It doesn't have it's own battery like the Solio. I've read varying reviews of the Solio stuff, very "it's good" to not very favorable. All the reviews of the Powerfilm gear that I've seen are very positive. Personally I'd rather have the charger and the batteries in separate pieces.
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JohnE

"and all the lousy little poets
comin round
tryin' to sound like Charlie Manson"

The Future/Leonard Cohen