From the Harvard corporate governance blog:
Fenwick has collected information on the corporate governance practices of publicly traded companies in order to counsel our clients on best practices and industry norms in corporate governance. We have collected this data since 2003 and believe this unique body of information is useful for all Silicon Valley companies and publicly-traded technology and life science companies across the U.S. as well as public companies and their advisors generally.
It's a very useful set of data.