I think tts ship integration would be cool. Like the computer in Star Trek. I don't believe players should have the ability to use tts individually, though. If it is included, it needs to be a module you install into your ship/station.
Here's an idea: there should be an in game email system that allows you to send private messages to other players. This means that if you want to strike a deal with a player that isn't currently online, you can send them a message that they can read the next time they do come online.