Has anyone experimented with "per-user categories" as an extension? The
commercial wiki Confluence has this feature: any category (called a
"label") that begins with "my:" is local to the current user. So
people
can tag pages with their own categories for their own reference, and
these categories are not visible to other users.
So if you added to an article:
[[category:my:important]]
this creates a category "my:important" that's visible only to the
logged-in user who created it. So people can create their own locally
organized sets of articles.
DanB