Wiki farm" that allows you to intuitively create categories (and make your wiki private)?

I use Wikidot.com. Wikidot has the private wiki and category features that you are looking for. You can use tags to have an arbitrary number of tags, and/or you can use a "category:page" naming convention for organizing your content.

Wikidot provides powerful ways to organize and display your content whether by tag or by category.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.