From the discussions and comments I've seen, there's been a general consensus we should be focusing on Africa, but I haven't seen a lot as to which country in Africa we should focus on, if any. I think it would make sense, as focusing our efforts should make it easier to accomplish our goals. Here are my candidates for countries, but feel free to post your own, in Africa or elsewhere.
For the Americans on EVOKE, we have a special connection to the nation of Liberia. Founded as a colony for freed slaves, the nation is now trying to pull itself out of 20 years of civil war. I think efforts here would go a long way to help stabilize the nation and region, and the relatively small population might give us an advantage on a "per capita" basis. Also, Ellen Johnson-Surleaf is arguably one of the most competent leaders in Africa at the moment, so we might find an ally at the top that we might not in other nations.
A very sparsely populated country, Botswana has benefited greatly from the diamond industry and the fact that the country has had a stable, democratic government since independence in 1966 has made it one of the few success stories in Africa. Despite this, Botswana still has high levels of unemployment and one of the highest HIV/AIDS infection rates in the world. EVOKE involvement here could help rescue, or even amplify, this rare glimmer of hope.
Kenya, Tanzania, South Africa
While certainly all different in their own rights, I've grouped these together since they are "popular" destinations for NGOs, which gives us an advantage in helping existing efforts, although perhaps at the expense of more desperate situations. These countries also have had, recently at least, stable governments (perhaps with the exception of Kenya) and, especially in the case of South Africa, a considerable amount of human capital compared to the rest of the continent.