Check this out..,

Click on the below link, it will appear as though two identical pictures are on the screen, 800 people were tested to see if they could find the three differences in the pictures, only 15% were able to find them, I found only one after about 5 minutes and gave up, give it a try and leave a comment if you find them. This takes total concentration for sure!

http://members.home.nl/saen/Special/Zoeken.swf