I just got back from a month in Tanzania as a CA-3.
Best month of residency by far.
The posts above don't do justice to the fulfillment you get from delivering care to patients who need it-- not to make money, not because the gov't says you have to, but because they're equally human and need your help. You don't have red tape (for the most part) and they don't expect perfection-- just your best effort.
2 y/o kids hold their hand out as you put in an awake IV
Guy with femur fracture is told he is put off until tomorrow because the OR is out of steril cloths says nothing except, "I will be back in the morning".
My experience included giving a ton of lectures to anesthetists, rounding in the ICU, and helping with the 6 ORs. I saw incredible pathology managed with very limited resources. People die all the time for reasons you can't imagine.
EVERY American has so much more than they appreciate, and yet we ALL complain. Many people who will never have as much material wealth as each of us has at this moment do not project the victim-entitlement that is everywhere here.
There are always 10 good reasons NOT to go (kids, job, car payments, NBA playoffs...), but I've never met ANYONE who regretted deciding to do mission work in light of all these "reasons". BTW, my "reason" not to go was that I came back to a 37wk pregnant wife who was "left" with a 16month old... She was a missionary too!
PM if you want more info.