Have you ever planted an herb garden and then forgotten exactly what was planted where? It can be frustrating trying to recall which little seedling is which. Labeling your garden at planting can save some headache. Because ceramic stands up to a wide temperature range, it's an ideal material for those little signs that indicate what seeds were planted where. Many crafts stores carry them, or you can craft them yourself with raw clay or preformed bisque plaques.
Most home improvement stores carry ceramic house numbers. Some are simply individual numbers that can be set into the side of the house or into a brick wall or mailbox. These require some building skill if you are doing masonry work. More pricey would be a custom-painted sign that might have a picture or the family name painted on it. If you've named your house, a ceramic sign would be ideal for letting the world know.
Many people enjoy placing signs in their yard just for the fun of it. For instance, a garden with a steppingstone path running through it might have a sign saying "Elf Crossing" or "Beware of Wabbits." Ceramic is far more suitable for such a sign than steel, and would stand up to weather better than wood.
Even the most mundane signage can be dressed up a little by using a ceramic sign rather than ordinary wood or steel. "Deliveries in the Rear" or "No Solicitors" carries a less stern tone when expressed via a decorative, glazed sign that could almost pass for a garden statue.