Many Canadian NGOs have a presence in Nicaragua. You can find out more on their websites:  

• Canadian Red Cross
• CARE Canada
• Change for Children
• Christian Children's Fund of Canada
• Co-Development Canada 
• Habitat for Humanity (Canada) 
• Horizons of Friendship
• Interpares
• Oxfam Canada
• Pueblito Canada 
• Save the Children Canada 
• SOS Children's Villages (Canada) 

To learn more about the work of Canadian NGOs accross the world, take a look at the Ontario Council for International Cooperation and the Canadian Council for International Cooperation.  You can also check out the Canadian International Development Agency (CIDA) to learn more from the Canadian Government's point of view.