RFCs and Best Practices

I have found it amusing browsing the list of RFCs in my spare time. It is really entertaining to me and good to learn how tech stuff work. But there is more into RFCs than Defining standards and Protocols. Some of them provide Best Current Practices (BCP) and information for the information community. Here are three of them:
RFC2196 - Site Security Handbook
RFC2504 - Users' Security Handbook
RFC2505 -Anti-Spam Recommendations for SMTP MTAs