Heather Hedden, of Accidental Taxonomist book and blog fame, published a new article on licensing taxonomies. She discusses a surprising variety of unexpected issues you can face without a thoughtful, customized taxonomy and she provides resources where you can find open-source, or license, taxonomies and controlled vocabularies, including the Taxonomy Warehouse, and the University of Basel Library, the Basel Register of Thesauri, Ontologies & Classifications (BARTOC). .
There is also a multiple-choice survey, which results she will post.