Web pages are designed to be read by people, not machines. Consequently, searching and reusing information on the Web is a difficult task without human participation. Adding semantics (i.e meaning) to a Web page would help machines to understand Web contents and better support the Web search process. One of the latest developments in this field is Google's Rich Snippets, a service for Web site owners to add semantics to their Web pages. In this paper we provide an approach to automatically annotate a Web page with Rich Snippets RDFa tags. Exploiting several heuristics and a named entity recognition technique, our method is capable of recognizing and annotating a subset of Rich Snippets' vocabulary, i.e., all attributes of its Review concept, and the names of Person and Organization concepts. We implemented an on-line service and evaluated the accuracy of the approach on real E-commerce Web sites.