Are there any books from where I could learn in detail about well established ontologies like FOAF, SKOS? Thanks

Where can I find a good sample triples (RDF preferred) and Ontology (OWL preferred) data for learning and testing purposes? I would like the data to have the following characterist …

What is needed to help the masses of developers out there work with Linked Data more effectively? They are already learning and using OOP, Object/Relational Mappers, RMI, JNDI and …