Hmm...you could talk about cocaine or coffee/banannas in south america and how other countries (ie the US) have intervened, putting in ruthless dictators to either (try to) prevent coke from being made or allow the countries to still trade (aka a "bananna republic). Good examples of that are Nicaragua, Chile ( think), and maybe Columbia.

You could also do oil in the mid east, but thats an obvious one.

I don't know too much about oil, but I can help you out with Bananna republics, esp Nicaragua. I'm actually writing a thesis on it right now.

edit: I reread the question and you would probably need to do your own research besides just the charts.