Environmentally friendly drives in the past have focused on powering down when idle, quietness, etc...but SimpleTech I believe has really done well with this.
The SimpleTech ReDrive External Hard Drive has a bamboo-aluminum casing and really looks amazing. Why do I like it so much? The thought never crossed my mind that computers were anything but metal and plastic. Desktop computers could also become wooden maybe?

Simpletech writes, "A thick aluminum casing is used not only for durability, but because it’s the most recycled metal on the planet. It also acts as a heat sink, cooling the drive without the use of a fan, saving additional energy and noise."
They also claim the bamboo is locally grown. This drive also comes with online backup - 2GB free, or 5$ for unlimited upload/download.
500 MB for around $160 - not too bad.