Back in the day, Berin Kinsman created a tiddlywiki specifically for game organization, called the Ten Foot Wiki. Unfortunately as cloud computing took over the world, Tiddlywiki had to seal up some security holes and became harder to use . Let's share some world and campaign organization tools here.
I got in on the Realm Works kickstarter so it was cheap for me, but it's kind of the Most Bonkers detailed thing. The GM version is $50 though. :o Find it here.
Drivethrurpg has a lot of "adventure planners", which are pre-printed PDFs which have a lot of the most common shit in them (but they're typically for fantasy or D&D-a-like games). Now, I kinda like the Fat Goblin Games ones because they 1) use form fillable PDFs a lot 2) are often broken down into different types of pages so if you are like me and need like 500 NPC pages and 3 monster pages then you can do that easily, and 3) if you're Extremely Into It they'll even send you a hardbound print copy that you can fill out? :o Anyway, this is their category: Fat Goblin Games Gamemaster Journal section on Drivethrurpg
If you still want to try TiddlyWiki, it's still quite popular but the tools are a little bit more opaque than you might remember them being. Give it a try.
Anyway, post other campaign/world organization software and tools here!