http://www.fbi.fh-koeln.de/institut/labor/Bir/thesauri_new/thesen.htm
The thesaurus collection is updated irregularly by the Laboratory for Bibliographic Information Retrieval (BIR). It includes both English and non-English language vocabularies as well as multilingual thesauri.
http://www.lub.lu.se/metadata/subject-help
Compiled by Traugott Koch, this listing includes thesauri, dictionaries and classification schemes that are available on the Internet.
http://www.controlledvocabulary.com/examples.html
Includes a brief description of sample controlled vocabularies and thesauri available on the Internet.
http://www.dbreference.com/thesaurus
Extensive list of thesauri and thesaurus websites, linked to extensive reference materials on all variety of subject matter.
Thesaurus online sites
http://sky.fit.qut.edu.au/~middletm/cont_voc.html#Thesauri
Classification schemes online
http://sky.fit.qut.edu.au/~middletm/cont_voc.html#Classification
http://www.collectionscanada.ca/8/4/r4-280-e.html
While the primary focus is on Canadian government vocabulary, listings of non-government thesauri are also included.
http://unstats.un.org/unsd/cr/registry/
The Classifications registry provides updated information on statistical classifications maintained by the United Nations Statistics Division (UNSD). Classifications cover products and activities and are international in language and scope.
http://www.ipsi.fraunhofer.de/~lutes/thesoecd.html
A listing of thesauri and other structured vocabularies available on the web compiled by Barbara Lutes; last modified in October, 1998.
http://zthes.z3950.org/thes/index.html
Listing of Zthes-compliant thesauri
available on the Internet.