The are a few good mods for CoH, such as:
Joint Operations: JO is basicly a mod that adds some coop and single player missions to your game.
Eastern Front: the mod adds the Soviet Union's Red Army and Nazi Germany's Ostheer. Conscripts are hella fun to spam out.
Modern Comabt: the mod is based around high-tech war between the modern-day Chinese and U.S. militaries. Incorporating all-new doctrines, units, artwork, and maps.
I just installed and played CoH:MC and it is really fun, it's like a whole new game. The Chinese are fucking tough to play against...THERE ARE TOO MANY OF THEM!!!1!!1!1111one