Star Trek Online's episodic additions are one aspect of the game that's generally been done right, especially thanks to player feedback. The latest series, Season Six: Under Siege, is bringing a new story, new equipment and most importantly, player starbases. These homes away from home can be built and customized by players and fleets can band together to construct bases for themselves.
Lead designer, Jeremy Mattson, has posted a dev blog detailing the inspiration for these structures and the purpose behind them. It's an interesting read, especially for fans of the source material.