New weapons, weapon changes and so forth.
I feel collision and impact damage should be increased for shields and hull, (but not armor.) Bare with me, I'm still on topic; imagine this tactic: blasting away a large vessels front armor, retreating and slowly shoving a large asteroid into him. I did this just recently and was very impressed with my genius, until it bounced off his shields at high speeds, (over 250) harmlessly. This wasn't no small rock either, I'm talking frigate sized. If this were to be done, ramming could become a viable tactic and a strategic part of gameplay.
With this said, since the game has a physics system in place, point blank range weapons such as drills could be added. Or on a more complex to program level: High tension cable harpoon guns. Tether the bastard and tow him into a rock.
Another missing weapon type is rockets. All current self propelled warheads are heatseaking missiles. Torpedoes don't count, they're torpedoes. Don't argue with me about semantics.