Every once in a while you find a site that really makes you say Ooooh and Ahhhh. Zoom.it is one of those sites. All you have to do is copy and paste a URL of an image and it will upload it to the website. You can then view the picture full screen and zoom into the image getting a better view of certain areas.
I used to teach the Renaissance and we would always examine the art from that time period. I would always point out certain aspects of the paintings. Zoom.it would have been a great addition to that curriculum. If you are ever examining a picture, this site is a must.
You can also embed the utility into a blog or website, as seen below.