"Every child has a currency." I remember watching that episode thinking, "When I have kids, they'll just do what they are supposed to do and I won't have to figure out their currency because I won't have to remove privileges nor will I 'bribe' my children with rewards." Riiiiiight. Those are clearly the words of someone who isn't a mother. Perfect children who are intrinsically motivated? Not mine. The best way to get a bedroom clean around here is the offering up of anything dinosaur (the Cubscout just wrote a power paragraph about becoming a paleontologist) or for the Clover, Hello Kitty. When bad choices are made, gone are those things they love the most (Fossil Fighters for DS, I'm lookin' at you).
In the same way, each of my students has their own area of interest/expertise/currency that can be used as a great motivator. At school, I'm not looking to get a bedroom clean or laundry put away, but rather planners filled out and assignments turned in or "kind talk" used. So out comes Mario, Angry Birds, or even the Solar System to help me, help my guys get the hard job of school done for one more day.