In my current iteration as an instructional designer I came across this list. It might be useful when putting together resources or elearning experiences.
An excellent collection of sources on all things World War II. Focusses on: life at the fronts; the holocaust; Japanese war crimes ("War crimes, what war crimes?"); photos & posters; and the nuclear bombing. With primary sources and well-organised.
This is a massive trove of free resources and information, based on the standards for the Massachusetts History Curriculum. It was created and is maintained by Bob Maloy of UMass Amherst and various students in the school of education.
An excellent set of digital source collections run by Columbia Uni. I've been meaning to save all these collections individually but it's such a massive task that I'm just saving the root pages of the collections. If you have a look through these you'll find some gems. And if you save them to the group you will have my undying affection (just please use the same tagging standards - it keeps the information findable).