@walter.almeida I haven’t done searching for vocabularies in anger yet, but I would like you start with obvious popular ones such as those which dbPedia uses along with foaf, rdfs, schema.org etc and also look at using cross referencing IDs for real things and concepts such as Yago (which takes all the Wikidata ontologies which is rich, but I gather also a bit of a mess being crowdsourced). Yago provides a mapping to schema.org (I think, going from memory here which is always getting me in trouble ).
Another excellent resource which I’ve again not used in anger is Linked Open Vocabularies where you can find lots of useful stuff including ontologies by ‘tag’ (keywords): https://lov.linkeddata.es/
I was going to look at building LOV’s data into VisLab’s SPARQL endpoints interrogator, but I’ve got enough info for now so am back to improving interactive search and explore of datasets. To start in going to include dbPedia and then explore by pulling in data from/via Yago.
So I can point to some useful links in those areas of anyone’s interest is peaked.