A backup battery attachment for the iPhone (called the iphoneck) is out. This would provide easy charging while traveling. The iPhoneck fits in to the bottom of the iPhone and takes a natural shape allowing usage along with charging. iPhoneck boosts the battery power of the iPhone by 60%.
The whole attachement weighs around 150grams (heavy!) and will leave you poorer by $35+ (approx Rs 1300).