You know those coffee sleeves used on paper coffee cups? Here's an interesting tidbit: Those sleeves go back to the invention of coffee, and their predecessors, called zarfs, were generally made out of metal. Anyway, the latest zarf innovation is the coffee "cuff," and it's looking to replace the traditional coffee sleeve with something worn on the wrist. Slide the cuff off, wrap it around your hot cup of joe, and you're getting a fix of caffeine and saving a minute percentage of a tree everyday. Once you're done with the coffee, slip it back on your wrist and enjoy the rest of your day while wearing a trendy cuff. Not a bad idea, though being green and trendy can be a bit expensive as each cuff sells for $70 and is available in a variety of styles.