In Civ1 we have 14 Civilizations and 7 playable; in Civ2 we have 21 Civilizations and 7 playable; In Civ3 we have 16 Civilizations (Vanilla) , 24 Civilizations (PTW), 31 Civilizations (Conquests) and all playable at once, so the more the improvements of technology, more and more Civs.
I would like to see this Civs on Civ4, wich are my prefered, cause they fullfill the earth map (I prefer play on earth map, instead random worlds), and could made many others continents with several civs, not only Europe and Mid-East, after all :
1. Siam / Khmer / Vietnamese / Thailand
2. Brazil
3. Abyssinia / Ethiopia
4. Ghana / Mali / Songhai
4. Bantu / Nigeria / Congo
5. Anasazy / Navaho
6. Malay / Indonesia
On other hand, I like the idea of Aussie Lurker of choosen civs from cultural groups, because this allowed have many civs and make everyone happy. After all, I think make a civ isn't so dificult, I guess. Over all in this foruns there many, and for every tastes. Otherwise the work is passing trough the modders. Wait and see.