Here’s one for Flames of War players who may want to pay closer attention to historical accuracy. Bill Stone offers a database of armies of World War II:
Armies of the Second World War” is an online database of day-by-day orders of battle and information about hundreds of division, brigade, and regiment-sized units in World War II. Information currently available in the database covers Commonwealth, Dominion, Colonial, Exile, and “Minor” Allied armies in Europe, Africa, and western Asia from 1 September 1939 through 7 May 1945.