Hi Jimmy--
I would caution against it, for two reasons.
1) We'll get the boring logistical one out of the way first: applying for the Match is infinitely easier, and more successful by every metric, when you are a senior medical student rather than an independent applicant. You will match, and match better, and match with less stress, if you don't take a year off.
2) As a newly-minted MD without a day of residency training you are dangerous. You should not, under any circumstances, present yourself as a physician if you do seek out a position abroad, but rather as a medical student. If you can accept that continuation of almost-doctor status, then I'd say you should take off a year between MS-3 and MS-4. Apply for the Fogarty or the International Doris Duke fellowships, or the CDC Hubert Fellowship.
If you cannot accept that 'demotion'-- if you feel that you are actually competent enough to treat patients immediately after graduating, even though in the United States you would be charged with practicing without a license, then your trip abroad is about you, not about helping anyone.
That, I'm sure, sounded harsh. But think about it-- if your heart is burning to help the developing world, why delay your training-- your definitive ability to help-- by another year? Think of what you could do in 3 years, or 5, versus what you could do next year. I'd encourage you to seek out residency programs that have established international electives, or even try to earn an MPH during a lab year. Surgery is slowly but surely coming around to the perspective that medicine, peds and FP have had for years-- that international exposure is a very valuable adjunct to clinical training in the States.
Surgery programs off the top of my head with such a perspective include UCSF, Mt Sinai, and Brown. Lots of others have electives in the pipeline.