C&C: One of the earlier games that began the trend of war simulation.
C&C Red Alert: A newer and better version of C&C but made about WW2, quite possibly the most important and well known games in this category.
Warcraft 2: Another similar game but made by Blizzard rather than Westwood.
Starcraft: Another of the same type, the newest one of them though, excellent.
F22 Raptor: the best flight simulator Ive ever tried before.

You might want to visit my friends website, Blargg's lava Domain for more detail.

Dont worry, I'll update this list and probably add some useful info soon enough.