It’s Me, and Here’s My Proof: Why Identity and Authentication Must Remain Distinct
http://technet.microsoft.com/en-us/library/cc512578.aspx

public / private data with logging on

Overview of the security principles identity, authentication and authorization.

Security

Ver clear description of the problem. Identity - "who are you?" - public assertion - locally unique. Authentication - "how can you prove it?" - secret response - non-unique. So biometrics are identity, not authentication.

I didn't realize the automatic boolean attributes part.

how to use mixins in Rails, with loads of useful stuff about testing at the end

Shoulda examples