The Kamusi Project is primarily a project to produce a free online dictionary for Swahili. However, its scope includes other African languages and also some non-African languages.
You can get a sense of the system in action by going to http://kamusi.org/kamusi-dictionary-terms-first-100-words and clicking through some of the links among concepts in the demo data set.
Read more about the Kamusi Project at http://kamusi.org/what-is-kamusi , http://kamusi.org/questions , and http://kamusi.org/explaining-kamusi
The project also houses quite a few Swahili learning resources - explore them at http://kamusi.org/swahili-learning-resources