If
you are a Mac user, you probably need Tinderbox. It is a tool that is
difficult to describe; it qualifies as an outliner; a web-page
generator; a kind of mindmapper; and an easily programmable
information-management environment. Check it out here.
This screen cap shows only one of several views of a Tinderbox file. And it talks XML.
They’ve been working on a Windows version for quite a while; hope it shows up soon!