What is this?
Large sites tend to have Site Maps that let the user see all the pages on the site in one single interface. Wikipedia doesn't have one because it's just too big to even imagine something like that (though I've tried). Now, this isn't a site, it's an userspace, but it's a big one with a lot of pages. Hence, it's got a map.
No, it's not an actual graphic map, but it does give one a tree view of all the pages inside my userspace. Everything is arranged in layer, or directories, and everything inside a directory is sorted alphabetically.
If it's a red link, that means I'm planning on making it in the near future. Don't worry about it.
Also note that there are some pages listed here that you can only get to through this page (unless you've memorized the URL). Those pages are usually just support pages that hold up the rest of my userspace, so you probably won't get much out of them unless you're a developer.