I would love one of these, the flag has a magnet sandwiched in the middle so you can put a card in there.
Stickers of course love em.
These are postage stamp magnets, the scalloped edges are made from felt.
This is another card holder - the donut is a magnet that you can sandwich a card between.
You can see more of these lovely lovelies at Japanese sites Decole Chocoa and also at Page Room unfortunately they only ship in Japan.
There is a small selection you can get online at Pancake Meow also other photos on Flickr and suggestions as to where you can buy.