I've seen so many articles about the semantic web it's a pleasure seeing someone actually doing it.
OpenCalais is a free (for under 50,000 requests/day) service analyses unstructured data and returns structured metadata, really, really quickly. And that metadata links to related 'packets' of 'Linked Data'. That's pretty meaningless without seeing it in action. But try pasting an article into http://viewer.opencalais.com/ and see how it breaks the data down into social tags, entities, people and events down the left hand side.
Sure it's a roughasgoodenough approach, but it still impressive, and has allowed many organisations to free up human resources and speed up throughput (and improve accuracy) when processing large wads of information. Or you could simple use it to add tags to you blog posts...
As Tom Tague says, "Match up a geek with a domain specialist and see what happens".
Tim Berners-Lee talks about Linkded Data on TED:
The following are just links and terms for me to follow up on when I have time but...
Linked Data W3C standard http://linkeddata.org/
OpenPublish (based on Drupal) http://www.opensourceopenminds.com/openpublish
Powerhouse Museum (kEMU, REST API,
OpenCalais Gallery of parsers