Porters for explorers, cattle for Masai and other herder types, slaves for Swahili Arab sorts and Ruga-Ruga. Camels are an option too, I guess (if "The Moutains of the Moon" is accurate in that regard).
Little dioramas are a nice idea in theory (and something I would like to get around to at some point), but at the moment I prefer to individually base them, as the figures are then more versatile, gaming-wise.