I have tried to gather in this place links to the job sites for the largest and most important multilateral development agencies:
This is a very good website from the United Nations in Denmark with links to multilateral agency employment websites.
Job Websites of Multilateral Financial Institutions
The World Bank (IBRD, IFC, IDA)
The International Monitary Fund (IMF)
The African Development Bank AfDB)
The Asian Development Bank (ADB)
The InterAmerican Development Bank (IADB)
The European Bank for Reconstruction and Development (EBRD)
Job Websites of United Nations Family and Similar Institutions
Jobs@UN The Canadian United Nations Association provides this website on jobs at the United Nations.
UN Jobs This is the website of a Swiss organization not associated with the United Nations, that nevertheless lists jobs at the UN.
The United Nations (UN) This website provides listings of vacancies for the UN system.
The United Nations Development Program (UNDP)
The International Labor Organization (ILO)
The International Telecommunications Union (ITU)
The Joint United Nations Program on HIV/AIDS (UNAIDS)
The UN Educational, Scientific and Cultural Organization (UNESCO)
The UN Food and Agriculture Organization (FAO)
The UN Industrial Development Organization (UNIDO)
The UN Childrens Fund (UNICEF)
The UN Environmental Program (UNEP)
The World Health Organization (WHO)
The Joint UN Program on HIV/AIDS (UNAIDS)
The UN Fund for Population Activities (UNFPA)
The United Nations High Commission for Refugees (UNHCR)
United Nations Institute for Training and Research (UNITAR)
United Nations University (UNU)
World Food Program
The World Trade Organization (WTO)