The Southern African Human-development Information Management Network for Coordinated Humanitarian & Development Action(SAHIMS) publishes free GIS data for a number of African countries. From their site:

SAHIMS GIS Data server offers easily accessible standardised data provided by various United Nations, non-governmental organisations and government agencies. Datasets in this catalogue are downloadable without any charge. It can be viewed and manipulated by using most popular GIS software. Metadata is attached to help the user have a better understanding of data sources, applications and copyright.

And from the SDI-Arica (Dec 08) list comes the pointer on weekly exports of OpenStreetMap Africa as shapefiles (and Garmin)