An Entrepreneur in London aims to turn 26 unused London subway stations and bomb shelters into shops and tourist attractions. The company Old London Underground Co with the CEO Ajit Chambers have raised 200 million pounds ($319 million) from investors. The first station is to be opened in 2012. The vision of the company is to unlock the value of historic underground real estate that had largely been forgotten.
This has actually happened before in Sweden when the company Bahnhof renovated the old bomb shelter "Pionen" and turned it into a data center with a nice result:
Source: Bloomberg, Wikipedia