An Introduction to OpenSSL Programming (Part I) by Eric Rescorla (the author of the main SSL/TLS book). This is a good companion piece to the book.
Use OpenSSL with Asynchronous Sockets, I/O Completion Ports and Ceritificate Signing has a lot of useful details on mixing and matching SSL and sockets.
Secure programming with the OpenSSL API, Part 1: Overview of the API article from developerWorks.
Cleaning up the build process for OpenSSL on Windows: http://codefromthe70s.org/sslimprov.aspx
The OpenSSL mailing list is at: https://groups.google.com/forum/?hl=en&fromgroups#!forum/mailing.openssl.dev
This is a copy of the original SSLv2 spec: http://www.webstart.com/jed/papers/HRM/references/ssl.html