MarsHome.org (Popularity: )
http://marshome.org/ The Mars Homestead Project - building the first permanent settlement on Mars utilizing local materials.
The L5 Development Group (Popularity: )
http://L5Development.com A privately funded, for profit, space exploration and development program whose initial business plan is to build space colonies at ...
1000 Planets Inc. (Popularity: )
http://www.1000planets.com/ Company news and activities - a for-profit space venture looking at space transportation and colonization opportunities.
Blue Origin (Popularity: )
http://www.blueorigin.com/ Aerospace R&D company working on spacecraft and launch systems with the ultimate goal of contributing to an enduring human presence ...
Space Studies Institute (Popularity: )
http://www.ssi.org The organization founded by Gerard O'Neill, with detailed information about his space settlement proposals.