The iPad isn't all that terrible for a built-in tablet speaker, but if you find yourself needing more sound in a small package, Logitech thinks they have the perfect speaker for you.
Their Tablet Speaker clips onto the back of most tablets and plugs into the 3.5mm audio jack. The battery provides up 8 hours of juice and recharges via USB. Expect to see this in September for $50. [Logitech]