Civ II is a great game where you control one of several civilizations in the struggle for supremacy that stretches from the beginnings of the bronze age to the space race and beyond!
These links are to many websites that have modpacks (bits of software you can add on to change the graphics, the civilization advances, and many other aspects of the game), maps, scenarios, and more! Check them out. If you find a good site that I am not linked to, let me know, and I will add it to the list!
One problem I have with the game is that when you have the computer create a new map for you to play on, you often get inconsistancies, such as tundra in the mid-latitudes, or jungle next to desert. I have created a few maps that are more 'realistic' that you can download through the links to the right.