For the past four years, the Danish government (partially through a contract with the OECD) has been putting together an assessment manual of entrepreneurship measures across countries.  It's a pretty straight forward exercise but one I think really helpful for most policymakers and new scholars.  The documents stated purpose is to: "First, it aims at providing a comprehensive overview of all available policy relevant indicators relating to entrepreneurship. Second, it rates the quality of each of these indicators in order to enable policy makers to evaluate the quality of policy analysis based on a given set of indicators. Third, the overview combined with the framework can serve as a starting point for future indicator development to ensure new indicators address issues that are need-to-know for policy purposes."

If you haven't taken a look at this report from FORA, it's definitely worth your time.  Read the full November 2008 report.