We've seen plenty of multi-functional iPhone cases over the past few years, but this one may be the most talented and clever yet.
The Rechargeable iPhone Speaker Amplifier Case (catchy name, huh?) features a rechargeable battery that could well double the life of your mobile, a subwoofer that amplifies the sound by about ten times and it's got a stand on the back to take good photos, or to put to good use when you're watching a video. Oh yeah, it protects you phone too, always nice to have that from a case.
To say it's got so much going for it the case is surprisingly slim AND cheap at just over $40 from Distinctive Style.