Have you never heard of the new microdata specification included in HTML5. I once read about it, but almost forgot it. But the Microdata: HTML5’s Best-Kept Secret article made me to remember this topic again. Similar to outside efforts like Microformats, HTML5’s microdata offers a way of extend HTML by adding custom vocabularies to your pages. The differences between Microdata, Microformats and RDFa Semantic Web technologies are primarily in the syntax.
Actually, despite its lack of publicity and HTML5’s still-incomplete status, microdata looks useful today and it is already being used by Google.