A guy at work just bought one of these. We connected it to an iPhone via bluetooth and have been having a mini rave in the office today.
It's only 15cm long and 4cm high but the sound is brilliant. The clarity is unbelievable for something so small and easily fills a big room.
Its pricey at about £150 but for the size, sound and convenience its unbeatable.
Jawbone Wireless Speakers & Speakerphones | JAMBOX