Cetacean related portuguese sites:

Forum Oceanos (portuguese and english)- discussion Forum about the oceanic environment with some information about cetaceans. It's possible to put questions to Azorean marine researchers;
National Rehabilitation and Stranding Network (ICN);

ECS - European Cetacean Society (english) - Scientific association, congregating european marine mammal researchers;
Sociedade Espanhola de Cetaceos (spanish) - Spanish Cetacean Society;
SMM - Society for Marine Mammalogy (english) - Scientific association, congregating worldwide marine mammal researchers;
EAAM - European Association for Aquatic Mammals (english) - Association for the maintenance of captive animals;
North Atlantic Marine Mammal Comission (english) - Inter-governamental body, for the cooperation in the conservation, management and study of North Atlantic marine mammals;

Research Institutions:

Centre de Recherche sur les Mammiferes Marins (french; english) - Marine mammal research cetner located at La Rochelle, France;
University of Victoria Whale Research Lab (english) - Research Unit at Victoria Un. (Canada);
Tethys Research Institute (italian; english) - Italian Marine Research Institute, which has several projets on cetaceans;
Centro Interdisciplinare di Bioacustica e Ricerche Ambientali (english) - Bio-acoustics research center, developing several research projects about cetaceans;
ALNITAK (spanish; english) - Research organization working in the western Mediterranean;
The Whitehead Lab (english) - Cetacean research lab. located in the Dalhousie Un.;
Marine Mammal Research Program (english) - Site of the Marine Mammal Research Program at A&M University, Galveston, Texas;
Sea Mammal Research Unit (english) - Located at the St. Andrews Un., this is one of the most important marine mammal research institution in Europe;
Nick Tregenza (english) - This UK based researcher has a very good page with information on his work, some of the problems affecting marine mammals as incidental captures in fisheries and collisions with fast ferries;

Non-governamental Organizations (NGOs):

International Whaling Commission (english) - The International Whaling Commission (IWC) regulates the whaling activity of the signatory parties;
World Council of Whalers (english) - Other institution congregating whales worldwide;
Whaling Library (english) - Pro-whaling site, that explains the arguments in favor of this activity;
World Wildlife Fund (english; french; spanish) - The main goal of the WWF is to stop, and eventually revert, the planet's environmental degradation;
Greenpeace (english) - International association devoted to the conservation of the world natural resources;
IFAW (english) - The IFAW works for the improvement of animal wellfare, worldwide, trough the reduction of commercial exploitation, habitat protection and help to endangered species;
Whale & Dolphin Conservation Society (english) - Organization dedicated to the cetacean conservation and wellfare;

General Marine Mammal Information:

Whale Net (english; spanish; parcially in portuguese) - An educational site, complete and extremelly well conceived; worth of visiting;
@Phocoena.org (english) - Scientific and educational information, both for general and specialized public;

Whale Watching:

Whale Guide (english) - Comprehensive list of worldwide whale watching companies;
Whale Watcher Expert System (english) - This little program aids in the identification of cetaceans sighted in the sea; it's fallible, but fun...