Well the summary pretty much says it all. I was going to suggest adding a glossary of terms to the site, but then I stumbled across it at the bottom of the XNA tutorials page. I think it would be generally useful to add the glossary to the help selections available in the context menu. Going a little further, maybe an expansion of the terms contained in the glossary to include more C# specific stuff would be helpful also. Nothing super fancy, or time consuming. Just a brief definition of things like polymorphism, encapsulation, derivative class, etc. I'm sure all of this is covered in the C# tutorials but having a quick reference handy would probably help out the newer members and those just learning. Just my two cents!
"May the mercy of His Divine Shadow fall upon you." - Stanley H. Tweedle, Security Guard class IV, The League of 20,000 planets