Smithsonian Institution
Nm Af A: Audible Artworks: Selected African Musical Instruments
Five traditional African musical instruments are highlighted at this Smithsonian site: two types of drums, the thumb piano (mucapata), harp, and whistles. Includes historical facts about the instruments.
BBC
Bbc: Bitesize: Music of Africa
This site is a part of the About Music site of the BBC, and this interactive site lets you explore various parts of Africa, their music, their instruments, their sounds. Requires Real Player.
Other
Dancedrummer: Traditional African Drumming and Dance
African drumming and dance are discussed in this interesting site. You can play with some of the interactive African style drums as well as access video and audio clips of the music.