Metalog - the semantic web query/logical system seems to be exactly what I've been looking for in terms of allowing simple exploration of Semantic Web technologies without all the lofty promises clouding things up.
Take a look at the quick guide and if you've ever read an introductory article on Prolog you'll be right at home... (In fact Metalog uses Prolog for it reasoning support)
It's helpful in that it allows you to translate the Metalog input into RDF triples and RDF/XML format, while playing with it in a pseudo natural language, so it drives home the mappings much more effectively than most tutorials I've seen.
I wish Metalog had OWL support too, but it's a start, I guess.