If you are REALLY in to World War Two military history, there is a lot of information on the web. One of the best places for free, primary source information is the Combined Arms Research Library (CARL) hosted by the Army Command and General Staff College at Fort Leavenworth, Kansas. This institution hosts a huge volume of information that is vital to training up the next generation of US Army staff officers. It really is amazing that this material is offered free of charge to the general public, and you should take advantage of it.
The Digital Library is where you want to be for your WWII fix. If you visit often, pay attention to the Recent Additions section to the right of the page - this will show the latest scanned documents that have been entered into the collection.
When searching, you will be searching through the scanned PDFs in the collection. My experience is that you have to be fairly specific in your search, and rarely get what you want back by putting in one word. If your specific search isn't found, go WAY general - like "3rd Infantry Division" - and just page through the results. The search is very fiddly, but it is worth browsing until you find what you want.
I have used CARL's digital library many times when researching articles, scenario games and just for fun. I will warn you - you can lose hours of time browsing the catalog. Below, I will list some of my favorite things in CARL.
Really Cool Stuff
OVERLORD Operational Order - This planning order is just a very cool historical document to see. Everyone knows what happened later, but seeing this relatively simple document on which the future state of the world was forged is just a neat thing to see.
Busting the Bocage: American Combined Arms Operations in France, 6 June-31 July 1944 - Not everything is primary source. This particular document is a thorough analysis of the challenges and solutions the US Army dealt with in France. It gives a great insight into the particulars of the fighting there. There are a great many papers with very thoughtful military analysis, including the theses of the Staff College.
The German Operation at Anzio - A detailed, post-war study of how the Germans did their thing at Anzio.
Swinging the Sledgehammer - There is stuff for non-US players as well! This thesis is a great study in German Tiger/Tiger II effectiveness.
Combat Lessons #6 - This document is amazing. This is something the Chief of Staff would publish to help the officers and men implement lessons learned in the field.
After Action Reports
I really like to read these to get a sense of what was going on on a daily basis during the war. While most of the documents are fairly good, some pages can turn out looking pretty bad, as the source may have just aged over time.
AAR 67th Field Artillery Battalion, 3rd AD - Really interesting insight into the detailed operations of an artillery unit.
So, go check it out! We have mentioned this a bunch on the podcast, but I wanted to spur those of you who have not checked it out to do so. Do not blame me if you lose a whole day searching through this stuff -- it is definitely something that can grab hours and hours at a time.