The Guide v2.0dev2 available.
The Guide is an application (a two-pane outliner) that allows you to create documents ("guides") which have inherently a tree (which you can modify as you please) and text associated with each node of the tree. The text itself is of the rich-text variety, and the editor allows you to modify the style and formatting of the text (fonts, bold, italics etc).
Version 2.0dev2 of The Guide is now available. This is a feature preview, work-in-progress version, and should be used for testing only. This version includes better hyperlink support and remembering node state. 2.0dev1 featured full multilingual support and changing node colors.