While looking into this, I found some excellent new maps of Darfur, by Centre for Development and Environment at University of Berne, Switzerland.
They can be found here.

Quote:

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The Swiss Federal Department of Foreign Affairs has responded to the growing demand for maps and geographical data by UN partner agencies, regional organisations, international and local NGOs, as well as local and regional authorities in the Sudan. The decision was taken by the federal department to finance the production of a series of maps for the Sudan.

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Also check out the links at the botton of the page.

These maps would make some great overlays.
But they're simply huge, 15119x10747 pixels, and there's 6 of them!
They would have to be cut into many smaller parts, and overlayed seperately.
Does anybody have the patience for that?