During my time with the Security Engineering Team at Mozilla, I had to understand the dynamics of revoked certificates. So I built a tool that crawls the internet and pulls revoked certificate information and populates a database. The script is written in Python and it multi-threaded for enhanced performance. The last time I ran the script against Alexa’s top million websites, there were more than 2.5 million revoked certificates. Below is a graph that shows the reasons indicted in those certificates of why they have been revoked.
The modularity of the tool allows you to do anything with the SSL/TLS certificates once you get them other than checking the revocation information. It is available on github from here.