JBL Micro Wireless Bluetooth Speaker- Each (Blue)
It's both smaller and louder than other similar products that I've used. The audio quality is better as well.  I'm no audiophile, so the poor quality of other devices didn't phase me... until I had this one to compare against.  I like the rotary volume control instead of \\"Volume up\\" and \\"Volume down\\" buttons.  The battery life is decent, maybe 10 hours.