merijn_v1
Black Belt
I have been wanting to play this modmod for years, but for a variety of reasons I have never managed to. In the other hand, here are my suggestions:
My ideas for new civs:
SWEDEN:
Make Sweden a separate civilization from the rest of Scandinavia:
-Spawns at 1050 AD in Stockholm.
UP: Nobel Prize: Number of Great People required for Golden Ages is reduced by half.
UU: Hakkapeliittaa (Or however it is written), replaces Cuirassier, earns experience 100% faster. Carolean (replaces Musketman, see below), +25% when attacking or defending cities.
UB: Borg (Castle) Does not become obsolete with Economics.
UHV:
-Control or vassalize Denmark, Norway, and the whole Baltic Sea by 1750 AD.
-Have 20000 culture by 1900 AD.
-Be the most technologically advanced civilization in 1900 AD.
(I would have suggested doing the same with Norway but that would leave little space for Denmark, besides it has spend a lot of its history joined with Denmark or Sweden).
I create a modcomp which includes Sweden to the game.
http://forums.civfanatics.com/showthread.php?t=529280
Other ideas I have are Belgium, Canada and Australia but my brain is kind of dry for them.
Canada is already in the mod. Australia is a modcomp (download here). I don't think there is much room for Belgium.
-Add Shinto as a religion. It spawns with Japan, but the Japanese have both Buddhism and Shinto.
There is a major religious overhaul pending. Adding Shintoism is a part of that.
-Also, is it too much to ask for two unique units and buildings per civ?
I also created a modcomp which does exaclty this.
http://forums.civfanatics.com/showthread.php?t=454952
I am sure you have heard about History Rewritten, because it has plenty of ideas you could borrowbesides some that would be out of place in DoC.
Leoreth has already included many features of HR. (I think it's the mod which provided the most ideas for DoC of all mods) I don't think there is much left of HR that does fit into DoC.

I suggest take a look at this list. It's a list of all expansions for DoC.
http://forums.civfanatics.com/showpost.php?p=13447583&postcount=2