Spatial data analysis is an important tool for geographers, planners, sociologists, and others, and this well-designed site by the Center for Geographic Analysis at Harvard University will be a real boon to anyone with an interest in Africa. As the introduction to the project notes, this site helps interested parties "accumulate both contemporary and historical data supplied by researchers and make it permanently accessible online." First-time visitors will notice that there are a number of data layers that can be toggled on and off as desired. A good place to start is by clicking on the "Map Layers" to view a topically organized list of the layers that are currently available. These layers include environmental data sets, historical maps, governance data sets, and linguistic distribution layers. In the "Places" tab, visitors can toggle on and off data sets that display administrative divisions, farms, schools, and so on.