We some plan to begin using "chalkink" markers instead of chalk. It is what Starbucks uses on their signage. It looks more like marker, but washes off like chalk does.
Here are some photos of the new wall treatment in our walk-in cooler. We applied a thin wood veneer to the metal and painted the top portion with chalkboard paint. It made a huge difference in the ambience and also gives us lots of flexibilty in terms of writing on the walls.