This iBamboo speaker is a foot-long slice of natural bamboo that was cut be lazer, and finished by hand. The wood is hollow and naturally amplifies the iPhone 4's built-in speaker. The most different is it requires no electricity.
As seen in the vid below, you simply slot the phone into the wood. It magnifies the sound significantly, including the stereo effect, though the sound quality can't really compare to conventional speaker systems.
Brooklyn-based creator Anatoliy Omelchenko wanted to create a product that uses as few resources and energy as possible. He has also made an edible spoon (which comes in three flavors) to cut down on plastic utensils.
This iBamboo would be priced at $25-$30, but maybe you can easily get a free iBamboo speaker nearby for free, because you can make it yourself! Anyway, it is a low-carbon life way.