Analogia (Andres Amador) has a lovely gallery of large scale sand circle patterns, made on the beaches of San Fransisco. The patterns are made by raking the sand , exposing the wetter, and therefore darker, sand underneath. Phidelity has other images of the same circles, and includes some designs to be considered for future circles. Glen Tregurtha in New Zealand is also a sand artist, and his gallery is here. I can understand liking the impermanence, seeing it washed away, rather like the Tibetan monks that spend days making intricate sand mandalas, and then brush it all up in minutes.

Updated 2015: some links broken.