ASSIST (American Slavic Student Internship Service):
Placements for teaching English in schools and businesses in Moscow or St. Petersburg for any length of time and any time of year

Association for International Practical Training (AIPT):
The International Association for the Exchange of Students for Technical Experience (IAESTE) is a network of more than 70 countries that coordinates on-the-job training for students in technical fields

Boston University:
Academic year, semester or summer internship programs available

CDS International:
Variety of internship programs including Germany and Argentina

Central European Teaching Program:
Internships

Global Internships:

Institute for International Cooperation and Development:
Six to twenty month internships in Africa and Latin America 

InternAbroad.com:
Search for paid and volunteer, academic and non-academic internships, as well as college credit practical training programs around the world.

Internships International:
Internships in Europe and Latin America

Mountbatten:
12-month internships available in NYC and the UK

People to People International:
International internships and traveling seminars

SummerJobs.Com:
Find summer internships by keyword or by location

Taking IT Global:
List of current internships from all over the world (Must go to Opportunities, then Financial to reach the internships)

World Affairs Council Internship Program:
Internships available in the following areas: International Visitor Program, Public Programs, Global Classroom Program, Membership & Marketing, Administration, Graphic Design and Webmaster.