http://pinktentacle.com/2010/06/futuristic-mega-projects-by-shimizu/
My favorite is the desert irrigation project.
Although it looks like that plan is for a saltwater based series of lakes in low lying areas. I’ve always wondered what would happen if you could irrigate desert areas with massive de-salinated salt water. The technology is of course not yet. Although there are big systems in California and Israel, they are too small by many factors.