Assignment #3: What's the best "green" product that isn't just "greenwashing?"

AdHack Assignments #1 and #2 proved to be a ton of fun and a great way to get ads created.

So we're back for more, more, more. Thanks to Alphanaut Boris Mann for the suggestion, here's AdHack Assignment #3:

What's the best "green" product that isn't just "greenwashing."

And further: What's the best green product you've made part of your life. Why'd you do it? What has it done for you?

All media types will be considered, so let your creativity run loose.