Toby Segaran, author of the super-fun Programming Collective Intelligence, has a nice talk titled Why Semantics? available about practical semantic web. If you immediately think of jumbo shrimp or military intelligence, you're not alone. But, his talk isn't pie-in-the-sky. He explains some of the contortions commonly used to shoe-horn freeform data into relational databases, then shows that these issues are being addressed using the graph databases that are part of the semantic web effort.
His upcoming book on the subject is Programming the Semantic Web.
He mentions a few good resources:
|Sesame - a RDF data store|
|Exhibit from MIT's Simile project|
|Linking Open Data|