Jeffrey Zeldman’s Web Standards Advisor

"...Jeffrey Zeldman\'s Web Standards Advisor is a $49.99 extension for Adobe Dreamweaver. It includes two major interface

  1. The Web Validator validates your HTML and CSS and verifies the proper use of microformats, including hCard and hCalendar, for single pages or entire websites.
  2. The Web Standards Advisor checks for subtleties of standards compliance in nine different areas—everything from structural use of headings to proper ID, class, and
    element use. Nonstandard practices are flagged and reported in the Dreamweaver Results panel for quick code correction. A full report with more details and suggested fixes is also generated."