Green Power has a new sliding speaker for your iPod. Looks like it actually adds some class to the iPod nano and iPod touch, neither of which have built-in speakers. Think of it as a weak but portable dock, with twin 1.5W speakers.
The device can be charged via a miniUSB port. A full charge should last up to 12 hours for non-stop audio. Comes in your choice of a crystal hard case or half-mirror design. There are also other colors available.