The fine people from Jim Hendler's Mindswap group at the University of Maryland College Park, just
announced version 2.2 of their SWOOP Web Ontology Editor written in Java with a Swing GUI. I've been trying it from subversion occasionally and it's come a long way and now works well as a RDF schema and OWL Ontology editor for the regular person. I've recommended it to several people as the one to get started with. For me, it's also handy for analysing exactly what features of OWL are used in RDF schemas/OWL ontologies and what puts them in OWL-DL or other OWL species. Plus it's less scary than other ontology editing solutions...
Also it has Turtle support, so I gotta love it for that!