You can't have enough things on your fridge, there's always something needs to be pinned on it. But you don't always have to buy fridge magnets from the store, you can make them yourself. Take a look at these amazing fridge magnets you can create yourself.
Styrofoam, like the stuff from take away containers or from the grocery store, can be used to make your own stamps. (This site is in French. I tracked the photo to http://www.funnycrafts.us/printmaking-ideas-for-kids/, but there are no further instructions there. I guess they figured the pictures said it all.)