Reader, Is your cab light on? As I was checking into a conference yesterday, the lady checking me in complimented me on my eyeglass frames. After a brief conversation, while she prepared my badge, she asked me if I had heard the story about the cab light. Of course, I had not, so she went on to say this: One of my dearest friends told me this story. In New York, the taxi cabs used to have a light on top of their car to indicate if they were available. If you saw the light, you knew the cab...