Actually, what would be nice is a tech available only in the limited-colonization games that would allow you to change an atmosphere before building a colony. Maybe have to park a large ship around the planet, or maybe building a starbase would be better. I can't decide if it should work slower than the Atmosphere ConVersion facility.
I'd also vote for making remote mining more efficient in the limited-colonization games. If I can't colonize that gas giant, I'm certainly going to pull as many resources out of it as possible...
I don't think there should be a way to research other colonization techs, though. Defeats the purpose of the limitation. On the other hand, if the nomadic race ideas are ever implemented, maybe the idea of building facilities in space could be applied to building facilities in starbases around a planet. Perhaps a bonus for facilities based around a planet? Just a way-out idea, since we can't build facilities on ships yet. Although I've heard that the system-wide facility abilities can be incorporated into components already...