If you search for an image on Google Image Search and then mouse over the result, Google will let you find “more sizes” of that image. For example, I searched for [cow] and hovered my mouse over the first result. As you can see, there is a link to “more sizes” for that image:
When you click on it, you are taken to a special filter that only shows you that image, but in multiple sizes from multiple sources. Here is a look at that page:
As Alex Chitu said, this is a feature Bing had for some time and Google just recently added it.