I've found my old commandlinefu entries last week, dating back from 2009 when I was working full-time in IT.
My favorite is my solution to counter dynamic ISP IP addresses without a dynamic DNS.
ifconfig en1 | awk '/inet / {print $2}' | mail -s "hello world" email@email.com
Just need to setup a script in a cron job that checks if your external IP as recently changed.
