With literally dozens of tiny portable Bluetooth speakers hitting the market, it's hard to tell, which, if any, you should consider buying. JBL's Micro Wireless is one such model, and while it doesn't offer a major sound or price advantage over its competitors, its attractive design and built-in line-out cord for connecting non-Bluetooth devices gives it a leg up.
To be clear, this is a slightly different class of speaker from the Jawbone Jambox. The Micro is truly tiny, a mono speaker not much bigger than a Christmas ornament (yes, there's a hook for clipping it onto your backpack or a tree, for that matter) that weighs in at a mere 4.48 ounces. While it doesn't deliver incredible sound, it does offer impressive sound for its size, particularly if you're sitting just a few feet away from it (I have it on my desk next to my keyboard as I'm writing this).
While you can certainly plug it into a laptop and use it in wired mode (or pair it wirelessly with a Bluetooth-enabled PC), the other big application for it is to pair it with a smartphone or tablet. It's definitely a significant step up over the internal speakers of an iPhone or an iPad and plays considerably louder and offers some bass, though not a lot.