DBpedia is a crowd-sourced community effort to extract structured information from Wikipedia and make this information available on the Web.
RelFinder - Interactive Relationship Discovery in RDF Datasets
Now that we’ve published nearly 10,000 of our tags as Linked Open Data, you’re probably wondering what kind of cool applications you can build with this data.
Virtuoso SPARQL Query Form
Generating RDF from data.gov - Data-gov Wiki From Data-gov Wiki