I realize this is Civilization and thus the need for empires of old. Those are already filled in though so I'd like to see an expansion featuring some younger countries.
First off, all G8 countries(Since Russia, France, The United States, Germany and Japan are already in that leaves Canada, Italy and The United Kingdoms if they're not lumped in as "English") should be included due to their contribution in the past century. It could also make for an interesting national wonder in which these countries are allowed to host the summit every now and then.
Of course other younger countries would be included who have made a mark in history. I'm not adverse to still featuring older civilizations though, I think The Ottoman Empire is overdue to be featured among some others.
I realize that this is gonna come under attack for mentioning Italy and Canada(Though by the looks of these forums, primarily for mentioning Canada). I'm not quite sure where this sentiment is appearing from but it's overlooking key historical events.
Militaristally, Canada had one of the largest navies in the world during WWI and won many decisive battles on land during both WW's. Canada had the number one pilot(Billy Bishop although his kills are up for debate my historians) for the allies, scarcely shy of Manfred Von Richtofen who met his demise by... A Canadian. Also, Canada had one of the four main armies attacking Dieppe(Two American squads, One British, One Canadian) as they liberated what's now known as Juno beach.
Economically, Canada is one of the world's leaders.
Industrially, well this goes back to the G8(Or G7 in this case), one of the first 7 nations to be industrialized.
Historically, Canadian Lester B. Pearson was a leader in the concept of peacekeeping. This could make for an interesting advancement as well as a peacekeeping unit which I'm sure could have some very cool stats if someone thought on that one.
So as you can see, there is a uniqueness to this particuliar country, it just lacks the Hollywood fever that America recieves.
Anyway, my main idea was a 'younger Civilizations' pack but I've spent most of my time defending the idea of one country being included because I realize the kick-back it's going to recieve from those who know nothing but that of maple leafs and snow.