Antares is a 3D game of trading/spacecombat, in the line of Elite or Frontier. Some things you can do travelling with your spaceship include trading of goods, piracy, smuggling, mail delivery, different kind of missions...
It is in pre-alfa state.
Massively Multiplayer Space Trading and Combat game. This is an online strategy game, not a 3D space sim. Incorporating ideas from games such as Stars!, SE3, MOO, Tradewars, MUD/MOOs, Dune II, SimCity.
Fleet Command is a massive multiplayer browser game situated in a futuristic space environment. You can colonize planets and command fleets of civilian or military space ships. The game features economy, diplomacy and combat.