I seem to be getting a huge number of hits to my photo of a jar of snake wine from our trip to Vietnam. Sure enough, if you look on a Google image search, it shows up on the first page of results. Not sure why there's so much interest in snake wine though.
This image gallery, which has all my images up to when I bought my digital camera and changed to Gallery, gets huge numbers of hits. It seems to have massive Google Juice. I guess because they're flat image files, well named (not P1234567.jpg) and have been around for a long time helps.