Are we talking the web or in general? Text is surely not the most universal or accessible system for everything in real life. I seem to recall a story about a parking garage using the silhouettes of fruits in different colours to mark what floor you were on. For people with problems to remember numbers or read other information there was a fallback to a shape (e.g. banana) and if the shape made no sense to you there was a colour (e.g. yellow).