This is AMSA's list; it's very comprehensive, and you can search by country, etc:
http://www.amsa.org/global/ih/ihopps.cfm
Also, consider buying this book, it's filled with lots of great information about specific electives, country descriptions, funding sources, and can give you a lot of ideas for the kinds of things you'd want to do abroad.
http://www.amazon.com/Medics-Electi...9923131?ie=UTF8&s=books&qid=1183919164&sr=8-3
Otherwise, i'd say start googling... search for the country you want, or the kind of elective you want to explore (research vs. clinical, urban vs. rural, specialty, etc).
If you're interested, i know a decent amount about two specific programs, Himalayan Health Exchange and trauma surgery in S. Africa at University of Johannesburg. Just google those if you're interested, but i'd be happy to answer some questions.
Good luck!
Quid