I've seen these done on a couple different blogs. Drawing on foil with permanent markers is just so much fun.
I borrowed this wonderful idea from Kathy Barbro's fabulous Art Projects for Kids blog. http://www.artprojectsforkids.org/2009/03/this-project-helps-students-identify.html It hangs above my desk at work. I absolutely love it!
Here are some hearts I did with my class. The idea came from Art Projects for Kids. Everyone loved doing this, and they look beautiful up on the bulletin board. I've had lots of positive feedback on this one.