What The @#$%&! (Heck) is this #! (Hash-Bang) Thingy In My Bash Script | Linux Journal
Handy article to help explain shebang to people.
Public
Advanced Bash-Scripting Guide
And advanced guide to bash scripting.
The TTY demystified
Some history and details about terminals, their history and their working. Likely very useful for people who haven't encountered actual terminal hardware.