These may look like regular headphones, but the clever Zumreed X2 Hybrid Headphones actually double up as speakers too.
When you're using them as headphones they offer high quality sound and the cushioned cups eliminate any outside noise. However, when you want to share your music with other people (at parties and things please NOT on the bus), then you simply flip the switch and the drivers on the outside kick in. You can then even rotate the cups so that they stand upright and look more like proper speakers than just a pair of headphones.
The device obviously doesn't require any charging if you just want to use the headphones, but to use the speakers you'll have to charge the battery via USB, which will give you around four hours of playing time.
Available from Red5 for £119.95.