Incase you just came out of Vault 101 /fallout 3 reference. You may of heard that Infinity Ward is making a sequel to Call of duty 4 called COD MW 2. (Title is likely to change) Almost no information has been released but I will update.
Post any ideas you would like to see in COD MW 2 or any fixes. But if you want your voice to be heard I suggest posting on IWs forum located at this link-
http://www.infinityward.com/forum/My idea:
The US is in a war with China. We've never had a Chinese enemy in COD before. Facing millions of Chinese should be interesting and this would be a "total war" so nuclear weapons are definitely a possibility. You would play as 2 or more of these units: USMC, SAS, US Navy Seals, or US rangers. The one or two special vehicle missions COD's are know for could be one of these:
-Gunner of an Apache helicopter
-Flying a bomber that would drop a nuclear bomb or just regular bombs.
-Driver/gunner of a M1A1 Abrams Tank
-Side gunner with a Gatling gun on a transport helicopter.
-Gunner of an M2 .50 cal on a Humvee while being ambushed in an urban city.
It would be cool if the being missions were your on the border of China and your waiting for the official word to invade. That would be interesting to be in the first battle of WWIII.
Another possibility that hasn't been done in COD is defending from an attack on US soil. That would definitely keep things interesting. But I don't want the whole game to be defending, their would be offensive missions to take back Chinese occupied areas. So you might have to siege LA or New York city.