OwlAuthoringTools

What schema/ontology authoring tool should I use?

SWOOP - Hypermedia-based OWL Ontology Browser and Editor works well.
Protege is an ontology editor and knowledge base editor with support for RDF and a number of third party visualisation plugins. Uses ontology structure to build forms for data entry.
IBM Web Ontology Manager - Java servlet based (anyone tried it?)
Altova's Semantic Works - polished desktop app (MS Windows, payware, 30-day demo available), has the feel of a visual UML editor
Topquadrant's Topbraid - EclipseIDE plugin
M3t4.Studio Semantic Toolkit — RDF and OWL editors for EclipseIDE (currently free, closed source), seems a little beta
SeanPalmer has a Schema Aware RDF Editor RDFe. Runs as an interactive (Python) command-line app, providing prompts for instance data according to RDFS/OWL structure.
emacs : N3-mode, nxml-mode
In the swap project, we mostly write NotationThree files (with emacs or whatever) and convert them to RDF/XML with cwm
The GRDDL approach works...
- see HyperRDF: Using XHTML Authoring Tools with XSLT to produce RDF Schemas, and Fun with Embedded RDF and DOAP for the GRDDL profile, owl2sql.xsl -- a start at representing SQL schemas in OWL
- In the TAG, we have started using the violet UML tool and converting to OWL with XSLT. see Using RDF and OWL to model language evolution
pOWL - Semantic Web Development Platform
Triple20 - SWI-Prolog based visual RDF editor, sounds like it can handle big data