I love this fun idea over at DIY Life - take a vase, and paint it with chalkboard paint to get a writable surface. I'm sure you can see how something like this could translate into the classroom environment.
That special paint isn't too expensive, and easy to find at craft stores and Wal-Mart. I think it would be fun to paint plastic trays so each child could have a drawing surface that would also prevent chalk from rolling away. If you're ambitious, you could paint a portion of a wall or door with the stuff. My director would have my head on a pole for doing such a thing, but maybe yours would be into it.