I just joined to play and post on the shockwave and Rise of the Reds mods for C&C Generals Zero Hour.
If you have Zero Hour, this should be one of the first mods you look at. Shockwave does not change the basic playing, but fixes balancing issues and makes playing a whole lot more fun by adding a ton of new units, structures, generals powers and even three new generals: Armor General (USA), Special Weapons General (China), and Salvage General (GLA). The current version is 0.95, but 0.96 is comming out soon. Since getting it, I have never played regular Zero Hour. The people who made this also are making a different mod, Rise of the Reds, wich replaces GLA with Russia, but only has vanilla factions. RotR 1.5 just came out, which has improved AI, new units, and some other stuff.