I've also been irritated by this for years. People so easily use the word Africa to signify one place, one idea. After all this time that idea is still the homogenous heart of darkness. In this talk at TED, Chimamanda Adichie touches on this (at about 05:40) but it is framed within her bigger idea of the 'single story': we can all fall into the trap of viewing things, places, people, ideas, in this singular, one-dimentional way. It's limiting, unimaginative, and encourages us to emphasise differences, rather than notice similarities.

The online TED Talks is an amazing resource. From culture to science to arts to technology, it's an inspiring melting pot of cross-disciplinary ideas. I urge you to subscribe to their RSS or iTunes feed without delay.