Organizations

Humane Society International (HSI) - International arm of HSUS (Humane Society of the United States). Oversees and coordinates efforts worldwide, addressing wildlife, companion and farm animals, and the use of animals in research and testing.
http://www.hsus.org/ace/11672

Open Rescue - Focussed mainly on factory farming, giving aid, rescue and veterinary treatment to any animal known to be suffering and in pain. Includes reports from rescue teams around the world.
http://www.openrescue.org

International Fund for Animal Welfare (IFAW) - Works to stop all commercial exploitation and trade of animals by changing policies and practices through campaigns and grants to other organizations. Includes breaking news, publications, media center and current campaigns. Headquarters in Massachusetts, USA.
http://www.ifaw.org/

People for the Ethical Treatment of Animals (PETA) - Operates under the principle that animals are not ours to eat, wear, experiment on, or use for entertainment. Includes information on campaigns, action alerts and how to live a vegan lifestyle. Headquarters in Virginia, USA.
http://www.peta.org/

World Society for the Protection of Animals (WSPA) - International charity and alliance of animal welfare organisations. Includes education and awareness campaigns to raise the standards of animal welfare throughout the world.
http://www.wspa-international.org/

Fur Free Alliance - International coalition of over 35 animal protection organizations working to bring an end to the exploitation and killing of animals for their fur.
http://www.infurmation.com/