One small observation is that nearly all signs and announcements in Southern Africa are written in English (except in former Portuguese colonies, where it's all in Portuguese). In South Africa, some signs are also in Afrikaans. Road signs generally have pictograms.
This wouldn't be quite so odd, really, except that English is very much a minority language. So you have the weird disconnect, when travelling around Southern Africa, of having all the signs around you in English, but everyone around you speaking some other language, be it Xhosa, Zulu, Afrikaans, Losi, or what have you.
Most people speak some English, but clearly for many people it's very much a second or third language.
For me, the disconnect is quite noticable and odd because I'm used to the situation in the States, where the signage often follows usage. If you start to see Spanish billboards and signs, you can probably expect to hear Spanish on the streets, and if you see Chinese, you can probably expect Chinese dialects. To have the languages on the streets bear little relation to those posted was jarring.
Mozambique was a great exception. Signs were in Portuguese, and so was conversation on the streets. A Welsh linguist I met in Maputo pointed out that he was surprised that everyone spoke Portuguese as their home language; he'd expected a situation more similar to that in South Africa, where people would speak some African language on the street.