[development] Where to find 'taxonomy trees'?

[Lists]

Can anyone recommend sources for pre-organized taxonomy trees, available in
plain-text (or XML, or Excel, or other) form?

I'd like to download a category/taxonomy/clustering list that I could use in
Drupal, but that I could also use in FileMaker and to create an on-disk
folder hierarchy (in my local desktop filesystem, which is MacOSX.)

I thought that I saved some links to some of these, but sadly I can not find
the bookmarks from that research.

I envision that there is some .edu or .gov site that might have some
research into topical organization, and I believe some of these kinds of
sources were in my bookmark collection of a half-dozen such lists.

(Bookmark tools still don't match my brain's way of thinking. ;)

I've considered using the taxonomy structure of projects like 'dmoz', the
open directory project.

I'm also open to shared Drupal taxonomy lists, so that sites could 'mirror'
the structure (not content) of categories and topics, if they wanted to
'synch up'.

Thoughts? Resources?

Thanks,
--
Gary