Abu Dhabi part of the United Arab Emirates is seeking to build the "world's first car-free, zero-carbon-dioxide-emissions, zero-waste city."
What's exciting about it is that they're really making an effort to measure the carbon impact and effectiveness of their designs. Then we should get a wealth of data that will be helpful for modeling sustainable designs. They also have a goal to make this city profitable, and thus hopefully more developers will sign on to sustainable developments. Otherwise, it will simply be a novelty for the rich.