Many users of outlines do not consider the outliner as a dead end, but as part of a workflow that spans several applications. That means at a certain point the outliner needs to export structured information. There are a few standards that are emerging (like OPML, an outline format in XML) and some product-specific formats like Keynote’s. A good outliner will have an open specification of its output, presumably in XML to allow “playing well with others.”
So far as Web publishing, this task is called “rendering.” UserLand Frontier is probably the king of HTML rendering, largely because that is the main purpose of the product. It is scriptable by its own very powerful language, UserTalk, which also runs on the server side. The outliner is used to edit both scripts and outline content.
Tinderbox has the most flexible and capable rendering overall, in part because it allows so many sophisticated internal relationships and links. That, plus its agents, can be used—if planned well—for very sophisticated publishing. Tinderbox’s internal representation is XML, and you can build any sort of XSL stylesheet for export, typically to a Web site. But this, and writing export scripts, is pretty hairy business.
Some outliners have built-in export to popular formats: OmniOutliner to Apple KeyNote (and Word via AppleScript), and Inspiration to Word and AppleWorks. NoteBook and OmniOutliner export to OPML.