PhotosNormandie is a collaborative collection of more than 3,000 royalty-free photos from World War II's Battle of Normandy and its aftermath. (Photos date from June 6 to late August 1944). The main link goes to the photostream. You can also peruse sets, which include 2700+ images from the US and Canadian National Archives.
Use the enemy's own films to expose their enslaving ends. Let our boys hear the Nazis and the Japs shout their own claims of master-race crud—and our fighting men will know why they are in uniform.
Why We Fight is a series of seven documentary films commissioned by the United States government during World War II whose purpose was to show American soldiers the reason for U.S. involvement in the war. Later on they were also shown to the general U.S. public to persuade them to support American involvement in the war. Each of them is in the common domain having been produced by the US government, available online, and linked below the fold: [more inside]
Derailing a train isn't as easy as you might think.  (Declassified WW2 OSS training video.) [more inside]
Poetry in Hell contains a complete collection of poems recovered from the Warsaw Ghetto's Ringelblum Archives. The project, which took ten years to complete, gives English translations of poems that are shown in their original Yiddish. [more inside]
Channel 4's 100 Greatest War Films as voted for by their (generally more clued-up than average) viewership has plenty for you to disagree with, but much to recommend. Filmsite.org has a history of war films (as does Berkeley) for the completists among you. There are more war films from and about Vietnam and Indochina than you can shake a bayonet at (see also the 1999 NYT article, Apocalypse Then: Vietnam Marketing War Films to learn a little about the Vietnamese government's 1960s and 70s archive of war film). The [British] national archives have archived film from pre-WWI to the Cold War.