A bunch of designers were given free rein to think of what they would really like to see in London. (One of them was clearly on some drugs as they tried to make my old stomping ground "unglamorous Feltham" into "London's coolest area" - this would not just take some designers but every god that exists in the world and the universe and then it probably wouldn't work.)
I quite like the idea of an overground system though. Some Dutch architects came up with this who may well have been on some recreational drugs. Check out The Evening Standard for the full story.