One New York mother decided to let her 9-year-old son fend for himself in the city, and that mom would be NY Sun columnist Lenore Skenazy. In today's Sun, she gives the the play-by-play. Apparently the little guy had been craving some independence, so Seknazy left him at Bloomingdale's one afternoon with nothing but a map, a MetroCard and $20 -- including some quarters if he needed to call ("No, I did not give him......