Going for an exhibition, trade shows, - informative signage comes very useful. You can just tuck it in the trunk and ready to use in seconds.
Domain is like the shopfront of your business. You might be just starting a new business, with the actual shopfront you will need to thousands of dollars to dress up the place, stock-up the store...what's next? Wait for the first visitor to come. Have you consider before everything is moving, you might want to announce to the world the new business you have hatched.