Google Code: Web Authoring Statistics
Our friends at Google have been busy analyzing slightly over a billion documents, extracting information about popular class names, elements, attributes, and related metadata. The results are really interesting, not only as they provide a detailed insight into standard class names or id names, but also as the Google authors review the results and reveal some interesting insights into how Google interpretes the html data.
and revisit-after, supposedly used to tell search engines how often to recrawl the page. To our knowledge only one search engine has ever supported it, and that search engine was never widely used — at this point, it is nothing more than a good luck charm. A remarkably widely used one. More pages use the completely worthless than use the element!