This could be the world’s smallest Bluetooth speaker

It's certainly the smallest Bluetooth speaker I've seen weighing in at 0.7 ounces. The ultra-small wireless Bluetooth  iFrogz Tadpole Speaker offers very good sound for its tiny size. With the included carbineer, you can clip it onto key rings, purses, belts, etc. A 200mAH lithium-ion battery powers it for up to 3 hours. Recharge it via micro-USB. It’s available in four colors, plus white. It's not availabe yet, but it is expected to ship soon. It will sell for under $20. At the company website you can leave your email to be notified when the iFrogz Tadpole Speaker becomes available. 

http://www.zagg.com/ifrogz/bluetooth-speakers/tadpole#tadpole/8708?&_suid=13899385036250058492798625349895