I got this idea from one of pizzapi's responses to Anths-Girl's link.

Post an icon, fanart, wallpaper, or any other fan-made SPN pic, and we go try to find the pics used to make it. Then the person who found the pics posts an icon, etc. of their own.

This would be great for those of you/us who have icons where you really want to identify the original picture and can't quite figure it out.