I live in NY and do this regularly. It started for me several years ago when my children were younger and I was trying to find more playing time. I play along the F and R lines everyday while waiting on the train, using a Martin Backpacker and recently a wood flute which is a new interest. Most times the experience is more about doing it than income however I have had a few nice things over the years. A few years ago a guy was watching me and appeared to be sketching. He put a caricture and a note down in my case to call him if I played weddings so that led to a booking. Have sold a few CD's and got a few bucks. One neat personal experienced happened one evening. I had quit and was walking out of the subway in Brooklyn. About a block later a woman passed by me and said, 'that was really lovely what you played...' Though those don't pay the rent in a sense that's why we do it...