How good are your powers of observation? This game from the Audobon Society tests your photo comparison skills.
Try the game at 30 seconds -- if you get better than 20, I'll eat my hat! Even after playing it a few times I can't beat the 10 second version. The differences in these photos are so well placed that I had great difficulty finding them all without a time limit! It took me about 5 minutes to find the last detail on each of the photos.
Quite a fun game. I've included my own version in this post. There are five differences in these two photos. First to comment with them all wins something. Again, I'm not sure what, but something cool.
Bird Watching on Whidbey Island.