I have one of these. Solar charger, can be charged from wall too. Expandable with as many detachable charge packs you want/need to buy(holds internal charge with juice for 4-5 iPhone charges). Has built in flashlight, reading light, FM radio, SOS signal, and ultrasonic bug repellent. Fast charging in sun or on wall charge, charges pretty well in overcast and under tree cover also.
G3 Model
G4 Model
The G4 is basically the G3 with a 5000mah pack included, which you can buy for around $50 so cheaper for the G3 and a pack. If your looking for just a power pack, these are great. Why not have the ability to charge multiple packs anywhere anytime? Can get 2500 or 5000mah packs for them that can also be used seperate from the charger/radio.