Today only, Staples has a nice portable USB charger for only $9.99. The iEnjoy MyBolt Portable USB Flash Charger is normally priced at $49.99 however I have never actually seen it that high in stores. Still, today's price is one of the best I've seen.
For those unsure of the charge amount, 2600 mAh is enough power to give an iPhone a full charge. Some Android phones have larger batteries and therefore it will not offer you a full charge. It is however a great something to keep with you in case you are out for the day and your phone starts to die.
Perfect for iPhone, iPad, iPod, BlackBerry, Samsung Galaxy, HTC, e-readers, digital cameras, and other devices
USB output and Micro-USB input
High capacity: 2600mAh each