I played around with the comic strip and happy faces but liked the Image Chef best http://www.imagechef.com/ (not sure if I can make this a hotlink using the blogger editor??)
I have literally thousands of pictures stored in tubs (ugg) that SOMEDAY need to be organized and saw how this could be used to do that along with the photo organizers like Snapfish or Flickr. It was fast and easy to use so that is always a plus.
I could use it in the classroom to sort types of pictures. For example I could display pictures of various types of bacteria, viruses, and protists and have labels for them color coded or similiar graphics or stamps based on type. Students seem to always confuse which is which.
In IPC we are currently studying motion and Newton's Laws and I could have pictures that showed each of Newton's Laws and for all that showed Newton's 1st use one background or set of icons, for Newton's 2nd use another bacground or icons, and the same for Newton's 3rd. This could help kids to remember for example if the picture was mounted on a blue background and had a dog print watermark it was Newton's first.