IMPORTANT: Content?

[Amadeus]

Perhaps something along the lines of The League could do the trick. When I say "along the lines of The League" I mean something not as large as a saga but more permanent.

Perhaps a sort of a conflict in which two factions are involved who each seek for volunteer ships to join their cause. At first I thought of a conventional conflict. But since you speak of Space Pirates, it can be a conflict beetween a regular space fleet and a Space Pirate fleet. Or perhaps even a conflict beetween two competing Space Pirate factions.

By completing missions and destroying opposing ships, players could earn respect in a certain faction which will allow them certain benefits (ship upgrades, discounts and the like).

It would also cause some inter-player rivlary as not all people would be on the same side and would seek to destroy their opponents in order to earn respect.