This improbably petite device is the X-Mini II, a pocket speaker from Singapore devised to add a bit of oomph to your phone/laptop/MP3 player. But does it deliver? Bizarrely, yes. Despite a paltry 2.5W of power, the rechargeable device benefits from an expandable "vacuum" that behaves like a sub woofer to help churn out a believably rich amount of audio.
That said, should this still not provide enough music to your ears, you can daisy-chain a number of them together to fashion your own portable wall of sound. £14 from Amazon