Adaptive Blue have come up with a great idea for extending metadata to better describe products and media detailed / reviewed on a page. AB Meta is based on the eRDF Standard meaning that is is fairly simple and easy to learn how to use. An example they provide is what could be used for describing a book.

<meta name="object.type" content="book"/>
<meta name="book.title" content="Kite Runner"/>
<meta name="book.author" content="Khaled Hosseini"/>
<meta name="book.isbn" content="1594480001"/>
<meta name="book.year" content="2004"/>
<meta name="book.link" content="http://books.com/1594480001.html"/>
<meta name="book.image" content="http://books.com/1594480001.jpg"/>
<meta name="book.tags" content="fiction, afghanistan, bestseller"/>
<meta name="book.description" content="Story of an Afghan immigrant."/>

This metadata provides information that could easily be used to uniquely identify a book and is something that would be great to be used by search engines for product results. Their reasons for AB Meta are:

• Object-centric: Focuses on everyday things that we encounter around the web
• Semantic: Upgrades pages to be part of growing Semantic Web
• Lightweight: No complex markup, no changes to the body of the document
• Intuitive: The names of things and attributes are easy to understand for anyone
• Efficient: The meta headers are easy to get to without parsing entire HTML page
• Extensible: Additional attributes and concepts are easy to add
• Compatible: Alternative markup based on existing standards is supported

On their site they describe briefly some of the rules they plan for it, and how it should be interoperable with Dublin Core metadata. There are examples of object types for:

• Albums
• Blogs
• Books
• Gadgets
• Items
• Movie Stars
• Movies
• Recipes
• Recording Artists
• Restaurant
• Stock
• Video Games
• Wine

Best to keep an eye on this one to see where it goes and whether it gets taken up by any search engines.