Zooka ($89) is an attachable Bluetooth speaker that travels with your iPad. Clamp it on the top of your iPad (or use it as a standalone speaker for other devices) and your iPad just got a huge audio upgrade.
A 3.5mm outlet also gives you the freedom of using it with a non-Bluetooth device. The device is made of sturdy medical grade silicone making it both durable and comfortable to the touch while providing an ergonomic and comfortable grip!