Companies like members of NASA's Commercial Crew like Planetary Resources (operated by Google executives, James Cameron, Sir Richard Branson, and others) have been planning for a few years to build such a lunar station as a launch site for asteroid mining spacecraft to the far side of Mars in the near future, and for water extraction from those asteroids as well as extraction of iron and water from asteroids between the moon and Mars.
Modules for habitats and the station are now in development - there is even a contest for this going on. They also have already successfully been building and placing many telescopes into space for us all to use via computer very soon.
As for other resources, He3 or Helium-3 is available on the moon and is also to be extracted. Coincidentally, Homer Hickam (former NASA engineer) also wrote about this in a novel "Return to the Moon."
NASA leaders and the medical community largely agree that human health is the number one concern on such a space station, according to my studies in Preventive Medicine. This is why Astronaut Scott Kelly and a cosmonaut have begun spending a year at the ISS to examine body system deterioration and related matters. Russians have already spent a year and longer in space, but we do not have that data. In a year, we can compare Scott's health status to his brother astronaut Mark Kelly's status on the ground.
Initiating gravity on the space station may be the answer to end the deterioration. We'll know within 5 years or so, when the 2013 NASA Astronaut Class may be ready to go to Mars.