Last of all, here's an interesting site (HT to the Carpe Diem blog)that provides easy comparison of GDP per capita and groups countries in various ways (economically, geographically, even religiously). I wouldn't go so far as to use it to make sweeping generalizations. Particularly because it only provides a snapshot. But it would make a very good jumping-off point to discuss institutional constraints, resource curse, and a number of other topics that lend themselves to analysis.
I hope you find it interesting. Feel free to suggest some uses.