(It's possible that this has been suggested before; if so, please ignore. Suffice to say, the suggestions threads are rather daunting, heh.)
One of the few complaints I have with GalCiv2 is that all the races seem more or less the same as each other after a while. Even with their starting bonuses and unique abilities, they often end up playing much the same, especially in the endgame.
I don't know how many of you have played the boardgame Twilight Imperium
, but it's pretty good, and not far off from MOO/GalCiv, despite being made of cardboard and plastic instead of bits and bytes (though, sadly, there isn't a single-player mode).
Anyway, the most recent expansion, Shattered Empire
has an expanded technology tree which features one unique tech for each race in the game. This adds a certain level of personality to the races, and I think it's an idea that could easily be implemented into GalCiv. In a way, it already has: the Korath's spore tech. The Good/Neutral/Evil-specific specials are also similar, of course.
Expanding on this, you could also have special buildings for each race. The Torians could have a special enhanced farm and morale building to help with their teeming hordes of newborn babies, for example. The Drengin could have a tech that lets them sacrifice ships for research points -- "The Guns-to-Butter Directive" -- so they can cash in on their extra dominator ships when no longer at war.
These would go a long way to making the different races seem... well, more different.