I have visited several departments of mathematics in Africa in 1995-96
including Benin, Ethiopia,
By clicking on the country's name, you will find
some information on each country and the names and addresses
of possible mathematical contacts in these countries.
Below are some suggestions for help that an individual can give to these departments.
An easy way to help is to include the address of these departments on your mailing list of preprints and reprints. It is very expensive for these departments to buy subscriptions to any journals of mathematics. Some of them only regularly receive the notices and bulletins of various mathematical societies because they are sent to them free of charge by these societies. Note that resources are scarce and departments may not subscribe to online services such as Math Reviews. Even chalk for teaching is a non-trivial expense.
Another way to help a specific department is to buy for this department an annual subscription to a specific journal. This is not very costly in many cases: indeed, an individual subscription (made in your name) to a journal is rather cheap if your institution already subscribes to this journal for its library. For instance, the Annals of Mathematics, or the American Journal of Mathematics cost around $70 per year for an individual subscription.
Information on various countries in Africa is provided by the African Studies WWW at U. Penn.