GameSpot
GameSpy
IGN
UGO
IC-Games
Firing Squad
If you've never been there before, http://galciv.wikia.com/wiki/Galactic_Civilizations_Wiki is an excellent source for all things Galactic Civilizations related.
Some of the articles need to be updated to Twilight v2.03 standards. Other than that, it is a good resource.
Many sections still don't have proper documentation. It's better than the in-game documentation, but far from the high standard of many other wikis.
