I saw this on CNN dot com: Post-it Note Wars Rage in Paris
At the beginning of August, employees of Ubisoft, a French computer gaming company, put up an image from Space Invaders in their office window. The next day, BNP the largest bank in France and across the street from Ubisoft put up a Pacman in their window. And now across Paris, office windows are decorated with images created with Post-It notes.
They have a website of photos taken of the windows. You can find it at www.postitwar.com Some of the images are amazing.
My personal favorite is this one. It's in Amsterdam not Paris. The juxtaposition of classic European architecture with post-it images in the windows just tickles my funny bone.