Here is an idea of what I'm talking about:
|taken from hammers & high heels|
The window I have has vertical rectangular panes like this one, but with three instead of four. Some people knock out the glass and replace with painted masonite or wood. I, however, plan to paint right on the glass since it is still in good shape. I also plan to paint the panes first with magnetic paint, then with a layer of chalk paint on top, so it can be magnetic, too.
Also, they now make chalk MARKERS which look just like chalk but without the mess! As soon as it cools down a little outside I'm going to get to work on this! Can't wait!