BodyMedia - you wear it all day around your upper arm to provide various measurements to calculate energy output. Well. It's interesting and all but to date, I haven't decided whether I've wasted my money.
One of the more amusing aspects of this experience is that the armband assigns personal bests to various of its measurements: eg. highest number of minutes engaging in vigorous activity, highest number of steps taken during a day and so forth. It also measures sleep (how many hours of sleep one gets in a night), sleep efficiency (hours of actual sleep vs. lying down time) and then there's lying down time itself.
I rang in the New Year by achieving my best ever performance in both lying down time AND sleep efficiency. And here I thought Sloth was a sin.
(What do you suppose the lying down efficiency is of the aging witches butter fungus pictured above?)