Wall AC Charger USB Sync Data Cable for iPhone 4, 3GS, and iPod
I purchased this to avoid paying Apple's fancy price for an extra charger.  The wall charger arrived on time and worked as Amazon advertised.  I have used it to charge an Ipad and Ipod as well as the Iphone.  The USB connection between cable and wall plug doesn't quite fit as comfortably as it should.  But it does work - and the price was excellent.