Wish I could, I found it a couple of years back on a forum somewhere
However trusty old Google shows this
http://www.tineye.com/
TinEye is a reverse image search engine. You can submit an image to TinEye to find out where it came from, how it is being used, if modified versions of the image exist, or to find higher resolution version
and most importantly
Locate web pages that make use of an image you have created
Not sure if it was the one I used, it free but limits images, see the FAQs
PS just tried it, fail to find my PuG ones, so not sure how useful it may be