Space Ventures to Watch

Armadillo AerospaceWorking on Sub-orbital spacecraft. Active****
Bigelow AerospaceWorking on inflatable space habitats. Active*****
Blue OriginWorking on sub-orbital spacecraft. Active***
Interorbital SystemsCompeting for America's Space Prize. Active***
JP AerospaceAttempting to use airships to reach orbit. Active**
LiftPort GroupThe "Space Elevator Companies." Active***
Scaled CompositesWinner of the Ansari X-prize and will provide
Virgin Galactic with its sub-orbital ships.
Solar SkiffCompeting for America's Space Prize. Planning*
Space AdventuresArranged the flight of the first ISS tourist
and serveral more since. Also provides less
spectacular space tourism options.
Space Exploration Technologies (SpaceX)Working on low-cost launch systems. Active****
Virgin GalacticWill provide flights to sub-orbital space. Active*****

About the ratings:
The ratings are kind of nebulous but are meant to convey how successful a company is in relation to the other companies right now. A company's rating can change at any time simply by making notable progress. The rating doesn't reflect the quality of a company's ideas or plans, only their current relative level of success.

***** = Leader
**** = Above Average
*** = Average
** = Below Average
* = Poor