Data-Vocabulary.org

Since June 2011, several major search engines have been collaborating on a new common data vocabulary called schema.org.

The schema.org vocabulary can be used with both Microdata or RDFa 1.1 Lite syntax, and it has types for Event, Organization, Person, Product, Review, AggregateRating, Offer and hundreds of others.

See the schema.org blog for the latest news, and schema.org and FAQ for full details.