Committee on Non-Governmental Organizations from United Nations' Department of Economic and Social Affairs (DESA)
NGOs in a consultative status with the UN. The Advanced Search allows one to search for organizations based on a number of criteria: type of organization, geography, areas of expertise, etc.
NGO Database from United Nations Office on Drugs and Crime (UNODC)
List of over 2,500 NGOs involved in prevention, treatment and rehabilitation of drug addicts, alternative development, crime prevention (including anti-human trafficking and anti-corruption activities), and criminal justice reforms.
NGO Global Network
List of non-governmental organizations associated with the United Nations.