Please don't tell me a "Fuelband" is the wristband I see. And please don't tell me people spend extortionate sums of money on them. pls.
I have one, it's a pretty neat device. They cost $150 and track a bunch of stuff. My launch version went screwy after about a year and the replacement I got didn't fit well since they changed the sizing so I haven't worn it really at all. It serves as a watch but also tracks your steps, calories burned, etc.
This type of device is pretty popular nowadays. What sort of differentiates it from the other brands is that you get points based on your physical activity (the "Fuel" you've burned) and get rewards from an app based on meeting certain thresholds, etc. You have a leader board with your Facebook friends and stuff so in theory it helps make you push yourself farther to beat them. I was more active when I was using it for what it's worth.