If a day comes where I am deep in thought or upset or for some reason not extending a greeting first, they will not greet. Surely if we are to improve race relations it would be better if it came from both sides?
In African cultures usually the person who *approaches* (or e.g. enters a room) should greet first, hence your (sharp) observation there, you are spot on. (It has little to do with "status" or "ingrained beliefs about racial inferiority" - man, what bollocks, some of you are reading so much into something you don't understand at all, and are just guessing based on white-ignorant-views!) Anyway, it may well be perceived as rude if you don't greet (for whites it's quite normal not to greet strangers, at least not usually considered "off" - hence we often seem rude 'by default' to Africans). Also if I enter a room and the person in the room doesn't greet me *I* would regard that as very rude, however, in African culture I'm the one "being rude", so both end up offended. There are other rules/differences and it differs a bit between cultures (e.g. in some, men greet the women, sometimes age comes into it) but I think the "person who approaches" is probably the most common norm, especially in 'cosmopolitan' areas, keep an eye out for this, you'll see the pattern in many situations.
There are other differences that create misunderstandings quite easily, especially since both blacks and whites are mostly very ignorant of each others cultures (yes, ignorant BOTH WAYS, you WILL be surprised how little most blacks know about even the most basic 'western cultural manners'). A few examples: In African cultures it is common and highly respectful to greet or call a person, especially a male, by surname only - if you call them by first name it means they are far beneath you or you believe them to be beneath you. In Western culture if you call somebody by their surname or refer to someone by their surname only, without title e.g. "Mr", that can often be interpreted as *extremely* rude. It's also specifically disrespectful in African cultures to call esp. a male by his first name; if I am introduced to someone I would usually "instinctively" want to "allow" them to call me by my first name to indicate (mutual) respect - but it would be uncomfortable/unnatural for an African male to do so.
In African cultures, men are also supposed to introduce themselves to one another when meeting for the first time. So if you're sitting with some African colleagues that know you, and someone new walks in that they know and you don't, and nobody 'introduces you' - well, that may seem downright rude to you as you sit there 'waiting' for someone to introduce you, but in fact it would not be right of them to 'introduce you', you are supposed to introduce yourself.
As I recall there are also other norms that create misunderstandings but these may be 'fading'. For example in our culture if someone very important walks into a room full of people you stand up out of respect, traditionally (I think) they would sit down out of respect, standing would be disrespectful (as you should make yourself 'lower' than the important person).
Women are also in some situations not supposed to make eye contact with men because that's regarded as 'slutty', I don't know the ins and outs of that one though, but for a guy if a woman seems to avoid looking at you it doesn't necessarily indicate rudeness as it might seem.
The way we are so 'isolated' from our neighbours e.g. often don't even know our own neighbours also is less natural to Africans.
In our culture it is HIGHLY rude to invite yourself over to someone else's place under most circumstances, not so in African cultures, in fact if someone is e.g. having a social gathering nearby it may be rude not to stop by (not completely sure on this, but it's the impression I've gotten). (I recall reading a 'letter to the editor' once of a black person who had moved into a white neighbourhood and was complaining how rude and racist all the whites were for not having pro-actively *come over* for tea etc. - not realising that in our culture it would be rude to do that.)
If somebody bumps their toe or otherwise does something clumsy, *you* say 'sorry' (I don't completely 'get' that one). If gossiping, don't say the name of the person you're gossiping about, instead refer to them by description (e.g. 'that one who is driving the new silver BMW' or something like that).
Plenty more. These things are mostly so deeply ingrained it's difficult for either side to change their behaviour even when aware of the differences, let alone when in ignorance. It's a minefield out there.