Gosh, I'd love it if we could modify weapon stats. Speed, damage, energy used, rate of fire, range, etc.
Goodness knows that I've been feeling a bit limited in what I want to put on my ships; having moddable weapons would be eight completely different flavors of awesome.
I mean, I'm told we'll occasionally be getting new weapons from the team--and we still need weapons that fire in a specific direction and not just forward--but it'd be great to make our own, too, even if it's just a modification of the ones that come with the game.