I'm another pbwiki user, and I'm only doing it for one campaign right now. However, I may do it for every campaign I start from here on out.
There's a simple breakdown of the campaign word that expands as I work on it. Players can flesh out their character origins and I can look over them at my leisure. There are notes for all treasure gained, including where it came from and who it goes to. Said treasure has pcitures, and the players can do treasure division in-between games through the wiki. My wife takes notes on her cpomputer during each session, and those go up, so I have a complete record of who did what and when that all the players can access.
House rules are included. New classes and feats, changes to the core rules, and what books I'm planning on allowing. When there is down-time between adventures, that's covered on the wiki.
It's been a real organizational and inspirational boon.