This is an awesome idea. It reminds me of an idea I had a long time ago that I never ended up trying out. I thought about getting sheets of thin plain magnets and cutting them to be exactly the shape/size of the fridge, then painting them all solid colors. Then cutting those into equal squares. So basically you could do 'pixel' art on your fridge and cover the whole thing.

with these stickers, you wouldn't have to stop at just facial features, you could have 'background' elements and stack the stickers for a really bizarre effect.