Just spotted (and bought) this on mymemory. It's a great price for a rechargeable power pack, and for me it's much more convenient than having something dangling from the bottom, ahem, a la power monkey etc. It has a mini-usb out so can still charge other devices. And although it appears to be branded mymemory, if you look closely at the front image, you can see 'mophie' written there, so assuming you receive the pictured model, you're getting a mophie juice pack, which sells everywhere for £50-£60!!
mm11ipower works as a code for 20% extra off