During med school I spent some time with a surgical team in Africa...enjoyed it so much that I made it a priority to find an anesthesiology residency that would allow me to do a little international work. I always asked about this in my interviews...and got a huge variety of responses...anywhere from "No, there are too many required rotations to allow room for international electives" to "Yeah, we have residents go abroad every year...we encourage and financially support these efforts." Some programs require you to use vacation time and come up with cash while others work it into your elective schedule, send attendings with you and fund the trip.
I don't remember the program-specific details anymore, but I do recall that Yale, Vermont, Pittsburgh, Utah, UNC and Dartmouth offered some sort of international experience. Michigan and Maine did not...though that was a couple of years ago so things may have changed.
Hope this helps!