Well, there are reasons that many of these cultures haven't been done: most game writers are totally blank on what to think when they think of, say, a Stannic nation. They wouldn't know a Mamluk from a Knight, and ask them to point to where a Bactrian cammel comes from on a map, they'll just say "Bactria!" and run away crying.
I'd say it's pretty ditto with Polynesia, South America, and Siberia. The Far East at least has cool cinema and anime that the people can draw on. What to the Maya who still live today have? Textiles? The Stans are all poppy fields and ex-Commies...it's just a big blank area of knowledge.
I wish some publisher was listening, 'cuz I've had all these influences in my campaigns. I'm a Cultural Anthropology student, so bringing in real-world inspiration is fun for me. I've created Inca/Maya/Aztec settings where human sacrifice was as important as it was for them. I've got Polynesias/South Asias/Aulstralias/Carribians (though I think there's been some more specialized work done by other board members on the island cultures). I'm freakin' graduating as a Muslimist, so I know that history and development better probably than some Muslims do.

Siberian shamans and Russian culture and "What ever happened to Atilla's Descendants?" have formed big components of my research...
And honestly, publisher, if you were to do it, this would stop me from having to.
I've been surprised that there hasn't been a "monotheism d20," using as inspiration real-world religions and their fantastic tales: Milton and Dante and Jinn and Golems, Babylon and Leviathan, actual hell and actual heaven....okay, true, it's got a lot of that "irk the over-sensitive" quality, but so does calling things in the MM "Angels," and I don't see mass protests in the street.
If any publisher has plans for this, let me know, since I'm writing the setting full cloth, and it'd be nice to know someone else would back me up.
