World War II Timeline - a fantastic timeline of events filled with links to many photos and lots of information.
German Invasion of Poland - Lots of different articles
Army Group Center: Operation Barbarossa
Hiroshima Bombing Accounts - Two first hand accounts of what people felt and experienced during the Hiroshima bombings.
Holocaust Timeline - A fantastic timeline filled with pic's abd lots of information that you can link to about the tradgedy of this event.