Once Upon a Time in War is a photographic retrospect of the Great War, World War II, Korean War, Vietnam and the War on Terror.
Free Speech Doesn't Mean Careless Talk! World War II posters from the US Merchant Marine at War. More posters (Rivets are Bayonets, Drive them Home). There's lots of other cool stuff, like this brief history of privateers during the Revolutionary War.
Remember.org is a huge archive of the Shoah. It contains sections on the accounts of survivors and liberators (here is an account by Helen L. of her childhood in Auschwitz, here is Harry Herder's account of liberating Buchenwald, here is Jacques Lipetz account of WWII in Manila, here is part of a history of life in the Warsaw Ghetto), images from the camps and pictures of artwork produced by survivors (here is Mauthausen then and now, here is a picture of a prisoner at Dachau from this extensive archive of historical images, here are some drawings by Jan Komski, an Auschwitz survivor), and an extensive sections of excerpts of books written by survivors. Many of the images and accounts on this website are quite disturbing.