I recently stumbled upon these little beauties (just watch the video above) - though I must confess I've not yet tried them myself...(give me a few days and I'll report back). Tembo Trunks are not speakers, rather they are collapsible earphone amplifiers designed for iPod shuffle, nano and classic. Made from 100% non oil-based, high-grade silicone rubber), Tembo Trunks require no assembly and use no power. Just attach your earbud to the Tembo Trunks and you're away!
One thing they don't mention on the website, but perhaps they should, as the maximum volume output is 80dB Tembo Trunks would be great for kids...and their parents!
UPDATE: After having now tried these, I'm happy to let you know that Tembo Trunks are strong, easy to use and the volume is just right! And I love love love the fact that no batteries or charging required.