Apparently the United Arab Emirates is planning on building Masdar City as a zero carbon emission city of 50,000 people. Cars won't be allowed in the city. Instead, they will have some underground public transportation that is solar powered. They plan on recycling / reusing water with very high efficiency (80%). All in all, this city sounds like an incredible experiment in making mankind's existence on earth more sustainable.
Being in southern California where we drain water from hundreds of miles away to sustain our needs, being able to have 80% efficient water reclamation would be an incredible breakthrough, not to mention all the other feats they are planning. The really astounding thing is they are planning on beginning construction as early as next year.