Those two posts deserve likes 
Have you ever seen/tried wave machines? These things...
I have no idea how they're supposed to calculate energy usage, but 20 minutes jiggling - and by jiggling I mean barely moving - and it will tell you that you've burnt 600kcal. Almost exclusively used by women at the gym I go to, none of whom break a sweat whilst they stand and shimmy a bit.
My current favourite gym-user is the Asian Heston Blumenthal look-a-like who comes in wearing a sauna suit, which you'd be forgiven for mistaking for a tin-foil tracksuit.