Websites offering very brief encyclopedic overviews of World War II:

Freedictionary.com: brief overview of selected WWII topicshttp://columbia.thefreedictionary.com/World+War+II

Microworks.net:
   The Pacific War: The U.S. Navy http://www.microworks.net/pacific/

Wikipedia.com:

   Military Organization http://en.wikipedia.org/wiki/Military_unit#Units.2C_Formations_.26
_Commands  

  Japanese Army and Navy Strategies for South Seas areas (1942) 
   http://en.wikipedia.org/wiki/Japanese_Army_and_Navy_Strategies
_for_South_Seas_areas_%281942%29

   Pearl Harbor http://en.wikipedia.org/wiki/Pearl_Harbor

   Hideki Tojo  http://en.wikipedia.org/wiki/Hideki_Tojo

   Imperial Japanese Navy
   http://en.wikipedia.org/wiki/Imperial_Japanese_Navy

   Imperial Japanese Army
   http://en.wikipedia.org/wiki/Imperial_Japanese_Army

   Fast Carrier Task Force
   http://en.wikipedia.org/wiki/Fast_Carrier_Task_Force

   Destroyer Escort http://en.wikipedia.org/wiki/Destroyer_escort

   Convoy http://en.wikipedia.org/wiki/Convoy
 
   Torpedo Bombers http://en.wikipedia.org/wiki/Torpedo_bombers

   Armoured Warfare http://en.wikipedia.org/wiki/Armoured_warfare

   Motorized Infantry http://en.wikipedia.org/wiki/Motorized_infantry

   Air Support http://en.wikipedia.org/wiki/Air_support

   Dive Bombers http://en.wikipedia.org/wiki/Dive_bombers

   Army Air Force http://en.wikipedia.org/wiki/Army_Air_Force

   Strategic Bombing http://en.wikipedia.org/wiki/Strategic_bombing

   List of World War II electronic warfare equipment
   http://en.wikipedia.org/wiki/List_of_World_War_II_electronic_warfare
_equipment

   List of radar models of the Imperial Japanese Navy
   http://en.wikipedia.org/wiki/List_of_radar_models_of_the_Imperial
_Japanese_Navy
 
   Heinz Guderian: http://en.wikipedia.org/wiki/Guderian
 
   George S. Patton: http://en.wikipedia.org/wiki/George_S._Patton

   Dwight D. Eisenhower: http://en.wikipedia.org/wiki/Dwight_D._Eisenhower

   Chester Nimitz: http://en.wikipedia.org/wiki/Chester_Nimitz

   Douglas MacArthur: http://en.wikipedia.org/wiki/Douglas_Macarthur

   Island Hopping http://en.wikipedia.org/wiki/Island_hopping

   Military Logistics
   http://en.wikipedia.org/wiki/Military_logistics

   Military Supply Chain Management
   http://en.wikipedia.org/wiki/Military_Supply_Chain_Management

   United States Army Quartermaster Corps
   http://en.wikipedia.org/wiki/Quartermaster_Corps

   United States Army Signal Corps
   http://en.wikipedia.org/wiki/United_States_Army_Signal_Corps

   United States Army Corps of Engineers
   http://en.wikipedia.org/wiki/United_States_Army_Corps_of_Engineers