Dave Winer writes:
The OPML Editor is good for all kinds of lists, directories, project planning, designs. The tool can be used by professionals and managers,
doctors, professors, lawyers, accountants, writers — basically anyone who thinks for a living.
Another way of looking at it — RSS is great for news, but not everything is news, some things, like the distance between the Earth and the Sun, or the elements of the periodic table, don’t change. Or change slowly, like the teams in major league baseball, or the top home run hitters. For information like that, knowledge, representing the relationships between nuggets is what’s important, and that’s where outliners like the OPML Editor, that’s now in beta, excel.
Here is an interesting example.