Locating a Source Image - Tineye

On a few occasions, I am given an image that I need to find where it came from. This mostly happens with a client purchasing a stock image that is too small or wanting to use an image they found on Google. I stumbled across a great resource. http://www.tineye.com
TinEye Reverse Image Search 
 I take a quick screen shot of the image I am looking for. Even in cases where it has been altered I have had success finding the image. Then go to TinEye.com and load it up.