You may be aware that we do have a categories package in OpenACS which works on every acs-object, thereby allowing us to categorize even users, as they are objects as well.
I'm just wondering how to best integrate this from a UI point of view and if it is possible to mount a category tree of the category system to a special subsite, linked with the acs-object type "user" (well, okay, I guess the type is called differently, but it is before breakfast on a sunny day....).
Though I like the idea of root categories, I'm not sure what these categories would be, so that they are generic enough for all sites to use.
Either way I'm happy to have found someone interested in this topic, so let's continue this thread and talk about our ideas.