According to the
UN Regions my 50-country itinerary fails to cover:
Middle Africa
Western Africa
Western Asia (really, I thought I had something there)
Southern Europe (ouch, that hurts)
Melanesia (not surprising)
Micronesia (not surprising)
Polynesia (not surprising)
I'm not too worried about hitting the nesia's, but the others I should get too. Western Africa is easy to get route-wise, and Southern Europe has been ignored by me completely for some reason. I could hit that area without even adjusting my route so I'm not worried about that. Middle Africa though will require some rerouting if I'm to get to it.