TL/DR: See Bold.
My first suggestion i think is a nice one that shouldnt be too hard to impliment, Custom names for the games your in:
I think it would be a good idea if you could set your own cutsom name to each game you have joined, as a lot of them have the default name of "CALL OF WAR GAME"
If not at least the ability to add a little note for example "french game", "game where im playing spain" somewhere on the games page.
My second idea might be a little more difficult, but linking your account to facebook to receive notifications about game events, such as units arriving at their destination, an attack against you, day change, unit completed ECT. perhas with a custom timer of X minutes so youre not spammed with notifications every second.
If not facebook perhaps some sort of text message alert for premium members?
My third suggestion is to do with the trade agreements. this one i particulary like:
As we know you can send an offer to trade resources, units, provinces, or relation status (at war, peace, cease fire.)
I think it would be instrumental that there be some more options here, such as an agreement time frame. i will give examples below:
Trade 10,000 food for 7 days of peace.
Trade army unit for 2 days cease fire.
trade map share for map share, 5 days.
This would allow, if chosen a set amount of time that cannot be changed after agreement that must be honoured. As the game stands when trading for peace, or cease fire or other important trust bound things there is no way of negotiating a time share, i could trade somebody $100,000 for a weeks peace and after my partner accepts put them straight back to war.
This would of course be optional, one could ask for peace for peace trade for X days or "Undefined" or "until broken" which would mean when one party changes their relation yours changes. this would stop people from trading right of way or map share, and then in a few hours stop sharing their map, however yours is still shared.
These are a few ideas i have come up with to improve the game in the short time i have been playing.
Drazard.