Vitro - Integrated Ontology Editor and Semantic Web Application
Vitro is a general-purpose web-based ontology and instance editor with customizable public browsing.
With Vitro, you can:
Create or load ontologies in OWL format
Edit instances and relationships
Build a public web site to display your data
Search your data with Lucene
One of my previous blog posts talk about Protege ontology editor. One could use Protege 3.4.1 (latest release when this post is written) to create ontologies and import them to Vitro to create a powerful web portal.