Africa: A Biography: http://www.amazon.com/Africa-Biography-Continent-John-Reader...

The 'Dead Aid' book and others like it. There was a specific book on the Congo whos title I can't remember atm, but I will find.

Wikipedia is also good for context, and the associated link, for eg. starting at the second Congo war:

http://en.wikipedia.org/wiki/Second_Congo_War