Opera has several browser plugins and lively projects to build support for the Semantic Web.

One of most interesting plugins is the Tabulator RDF Browser Plugin. It's one of the few RDF tools that actually works.

The Tabulator Developers Notes ( and source code ) at MIT's DIG-CSAIL.

Interesting article on the slow takeoff of the Semantic Web.

Semantic web technology is marred in a chicken/egg paradox. The technologies are generally not useful unless they are adopted and implemented on a large scale and people are not willing to invest in implementing them unless they are useful. This is exacerbated by the fact that there are very high technology, business, and social barriers to implementing the semantic web.

Updated Oct 20 2008: new link

A really excellent example of what can be accomplished with a pragmatic approach to implementing RDF and Semantic Web applications, by Drs. Marwan Sabbouh and Joseph K. DeRosa at the Mitre Corporation. They use OWL ontologies to map between databases in three basic steps:

1. Express any software component’s formalism as an ontology,
2. Map the component’s ontology to the domain ontology, and thus
3. Integrate components at the semantic level without writing integration code.

The Semantic Grid takes the standards of the Semantic Web usch as RDF and OWL and combines them with the technology of Grid Computing, sometimes called the Computational Grid. There is a strong association between Grid Computing and SOA architecture.

One of the best descriptions from the article Semantic Grid is Laying the Foundations for the Semantic Grid (PDF ):

Jan 25 2009 - Added Named Graph links
Note to self Sept 10 2008 - This thing needs work.
Revised: April 4 2008. This disordered mess of links cleaned up, except for a few strays.

See Semantic Web at technorati.com.

Examples of RDF and stray stuff:

W6 vocabularies ( ontologies ) allow resource descriptions and reasoning based on the 6 questions : who, why, what, when, where, and how. ( better called "W5-H" ? )