Well, as a cataloging librarian, I can't resist responding to this one.

Most thesauri are specific.  They are usually produced by a specific group
of subject specialists to control terminology in their field.

For example, the National Library of Medicine (US) produces a thesauri of
medical subject terms, and the National Agricultural Library (US) has one
for agriculture and related subjects.  You have mentioned the Getty products
already, and the AAT.  All have the experts structuring the subject terms
that apply to their area.  The Library of Congress has two specialized
thesauri, one for graphic material another for the description of rare books.

The most general lists are maintained by those generalists, libraries.  Many
public libraies use the Sears List of Subject Headings.  The Library of
Congress publishes lists of subject headings (not a true thesaurus--but a
structured vocabulary), the National Library of Canada also publishes
subject headings in English and French :-)

To my knowledge, the library community is still working on subject thesauri
in the field of theology.

Yes, there are lists of thesauri, they are usually called bibliographies.
Go to a library and ask, typically a bibliography of reference books will
include a chapter on thesauri.  Just bear in mind the fragmented nature of
subject thesauri.  One-stop shopping isn't always available.

Marianne Cavanaugh
Associate Librarian
Saint Louis Art Museum