I was walking into a 7-11 here in downtown Boston and noticed that there was a height chart on the door. For a second thoughts of amusement park rides flashed through my mind, then I realized what its real purpose was. If you robbed the place, they could use the camera footage of your entrance and the height chart to get an accurate guage of how tall you are. Which takes some of the heavy lifting away from the the clerk who just had a gun in his/her face ("He was about 5'4"… no make that 6'4"…") As Boston locals are wont to say that's wicked smart.