The following websites provide information specific to World War II: 

BBC website links on World War II: BBC History - World War II;

Other websites providing access to World War II history resources online:
World War II Sites and Best of History Websites;

British and Commonwealth Navies in World War II: Royal, dominion and allied navies in World War 2;

The website of the Rome Branch of the Italian National Partisans Association on World War II, containing a comprehensive range of Italian documents, photos and information (in Italian): Seconda Guerra Mondiale.