My phone's been not charging well recently and i read on google that the chargers aren't very good, so i bought a new one and noticed this case, but not just any case, it had a battery inside this case, so you plug your phone into it, when your phone is low on charge, merely press the power button on the case and it will charge your phone.

 

It's probably old news to you lot but i just got one and it's quite immense, doesn't add too much size to the phone either considering.

 

http://www.ebay.co.uk/itm/281202092852?var=580246718072&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

i had one for my s2, really good idea imho

Aye fantastic idea. also good that you can put the charger in the case, press the button and it will charge the phone then battery.