I am a massive fan of 'Avorion' [Steam] as this Early Access space sandbox has a lot going for it and it just got a major update. I am also considering setting up a GOL server for it!
This new update will mean a re-design of your ships, so be warned. The flight model has been reworked and you now need to make use of three new blocks: Directional Thruster, Gyro Array, Inertia Dampeners.
It also introduces a group system, so you can group up with fellow pilots to explore and conquer the galaxy. You will see members of your group display on-screen and on the map, making it easy to find each other.
There's also now a server browser, making it much easier to join servers if you're planning to do some online play. The developer also enabled password-protected servers, making it a bit more friendly to manage if you want to restrict it to a community (like GOL).
It also includes tons of bug fixes of course, making the entire experience more stable.
I am thinking about running a server for it, but I need to know if there's interest in it. Let me know in the comments if you would be interested in it.