Categories are Useful.
So I didn't know much about the Category sections for Wiki until I started working on ours. Apparently the concept is pretty similar to the way our blog posts are tagged. It's just a way of organizing similar topics in the same place.
Used practically, that means if you find a subject you're interested in, you can look at the bottom of the wiki page and find the Categories that it belongs to. Of course, Link hopping always works too.
For example, here's our Fourze category:
http://www.wolfinspace.com/wiki/Category:Kamen_Rider_Fourze
You can see all the pages tagged as being part of the Kamen Rider Fourze category here. Generally the code for this would be {{category: Kamen Rider Fourze}} somewhere on the page.
You might notice that the episodes aren't filed alphabetically. That's because those pages are tagged {category: Kamen Rider Fourze|31}}. The 31 can be anything else, but basically that means that page will get filed under 31 instead of whatever that page is named. Since most pages aren't numbers, it seemed like a good policy to implement, that way all the episode numbers are at the front of the category.
This link is in the side bar, but here's a list of our current Categories:
http://www.wolfinspace.com/wiki/Special:Categories
About Spoilers.
By the way, I was looking at this wiki article and liked the way they tagged their spoiler sections:
http://catherinethegame.wikia.com/wiki/Erica_Anderson
I'd be okay with just lifting that template and using it to mark spoilers on our wiki.