Try out TinEye

TinEye is a reverse image search engine,allows you to search for an image to find out where it came from, how it is being used, if modified versions of the image exist, or to find higher resolution versions.
It is the first search engine to allow you to actually see how an image is being used. It drives home the notion of image accountability and integrity.

Image too simple to create unique signature
TinEye requires a basic level of visual detail to properly fingerprint your image. Try uploading a larger or uncropped version if possible, or another more detailed image.
TinEye's usage:
my first thought when I see an image I like is to see if there is a better quality one to be found on TinEye. Not only are the bigger and better images appreciated but also the links to the websites that are hosting those images.