Commercial space station

Rather than reiterate the fine ideas that have been presented so far,
I will merely add my favorite idea for getting a commercial space
station "off the ground" (literally and figuratively): launching large
module from Earth. This is based on the proposals for using the Space
Shuttle external tanks to build a space station. Rather than simply
using them for raw materials, you build them with everything (that
won't be harmed by cryogenic temperatures) already in place.

These could be put together in a roughly torroidal shape. To speed up
the process the modules could be added in diametrically opposed
pairs. Thus rotation can start right away, and the main EVA would be
binding the modules together. Also, for added safety in case of a
leak, the connections between the modules could be shut, perhaps
automatically.

++JohnWheeler