One of my favorite walks? From my apartment to my office, over the Queensboro Bridge. (I still haven't gotten used to calling it the Ed Koch Queensboro Bridge. Maybe one day.) It's about three miles, door to door.My new motto? "If the sky's clear, walk it, dear! If it's raining hard, swipe your MetroCard." Those rhymes are terrible, but the fresh air is nice. This week, I saw several discarded NYE accoutrements and a new street-art series: photographs of the back of a woman's head, an image that was pasted to a number of yellow poles.