Hey,
How about a voice chat/radio system?
It could be tied to a special block (ex. Communication Center) and would enable the player to directly communicate with other players. Different channels could be implemented too, like ship to ship, fleet, sector. There would have to measures to prevent spam though. Ideas would be that the other ship would have to accept a transmission or would be able to mute a player easily.
I got no idea how complex such a system would be, but it seems like a cool feature if you play on a bigger server.
What do you think?