Often stated questions are "Where can I find an ontology for XY?"
Much more helpful, I think, would be the answer to the question, how to find useful ontologies in general. So, what directories or search engines do you know to find ontologies? Or what are your ideas to make finding ontologies easier?
Just one example I know (I'll make a list from your answers):
Ok, here is the list so far (Thanks to all contributors):
- http://schemapedia.com
- http://swoogle.umbc.edu/
- http://iws.seu.edu.cn/services/falcons/
- http://watson.kmi.open.ac.uk/WatsonWUI/
- http://schemaweb.info/search/Search.aspx (no longer maintained?)
- http://dipper.csd.abdn.ac.uk/OntoSearch/SearchEngine
- http://protegewiki.stanford.edu/wiki/Protege_Ontology_Library
- http://www-ksl-svc.stanford.edu:5915/FRAME-EDITOR/UID-2&sid=ANONYMOUS&user-id=ALIEN (Ontolingua, not OWL or RDFS but a few interesting ontologies in there)
- http://vocamp.org/wiki/Where_to_find_vocabularies
- http://bioportal.bioontology.org/
- http://owl.cs.manchester.ac.uk/repository/