Howdy.
I've been wondering... how "moddable" is GC2? I've had a few ideas since I started playing about what I'd like to see in the game.
It would have been cool if one could use military starbases to dock starships for repairs, kind of like planets. Thus, these starbases could very well be used for defense along one's borders, or as forward bases when there is no planet near. Perhaps one could upgrade them with "Orbital Fleet Manager"-like modules or even allow them to construct military ships (but not utility vessels like Colonies or Miners).
Another idea was for one of those random game events: essentially the creation of a semi-sentient biotech parasite race (think a combination between Symbiots from Fading Suns, Mycon from Starcon 2, and Tyranids from Warhammer 40k). These guys would suddenly appear on a previously quiet planet and launch a merciless program of extermination on all nearby races. One would be unable to negotiate with them and, as a bonus, their means of planet colonisation would incidentally cause immense damage to the world, perhaps dropping planet quality drastically, or rendering it a toxic world.
Further, how about bringing religion into the game? Just for some extra flavour, one might be able to build a variety of temples and cathedrals for bonuses to morale, influence, diplomacy, and luck. This could be closely linked with alignment, with all shades of the spectrum having their own special means of worship. If one plays an overtly religious race, it could entail certain ethical imperatives, to be ignored at one's own peril (eg. playing an evil alignment means regularly and actively extorting, torturing or enslaving other races; if one's population feels you're not "evil" enough their morale will drop). Nice bonuses can be conferred if one sticks to one's morality.
Lastly -- and this is the big one -- why not diversify all the races at a much more fundamental level? After all, these are species that developed for millions of years without contact. Though they all use essentially the same framework -- manufacturing, research, economy, faith

-- their improvements look different and have small differences in functioning (one mp less here, one ip more there). If an alien planet is conquered, the native improvements would at first be unusable to the conqueror, who might choose to demolish them to build his own or, alternatively, research the xeno tech to render the extant improvements functional. Certain improvements, however, would be completely unique and usable only to their parent races. This goes for some technologies and ship types too. For example, the mystic race mentioned above could research propaganda technology for stronger influence, and even have propaganda cruisers, basically acting as mobile influence starbases.
I realise the size of these ideas: the penultimate one amounting to an entire expansion, the last one to no less than a whole new game. In any case, realistic or not, let me know what you think. It's fun to consider, either way.

J.