Many fast food restaurants have done pretty well with attached indoor playgrounds. However, some of us prefer not to feed our kids junk food every time we need some indoor playspace. There are plenty of structured or semi-structured gyms and such for children, but very few indoor playgrounds for simple, active freeplay. So here's the idea: have a playground indoors. Have an all-you can eat snack bar that is filled with only simple, healthy foods. Charge admission. The basic...