When you see an image of smiling people on an ad or a website, there's a pretty good chance it's a stock photo — a generic picture of some situation, like "Woman Laughing Alone with Salad." There are easily millions of stock photos online for download, usually for a price. But the WNYC Data News Team is adding a few more: photos illustrating quintessential NYC situations. They're free, licensed for non-commercial and editorial use and also available on Flickr.