If you haven't seen it, then take a few moments to go to the New York Public Digital Gallery, do a search and then see the options they have for sharing images. They provide the code for linking to an image as well as the code for embedding an image, like:
In fact, if you click on that photo, you'll go to its web page and see the link options on the lower right.
Having content shareable is what we all want. Nice to see NYPL actually doing it. I don't know who is the person behind this (perhaps Josh Greenberg), but whomever it is deserves "two thumbs up".