Maybe you should take the "One month GUI challenge" :), I wrote this for folks who are just getting started I believe that once knlowing the CLI gives you some confidence about uour computer and sets you up for easier learning in the future.
The example in your article was great (sort) - what other tools can't you live without on the CLI? Here are a few of my favorites:
- unique - sed - grep - wc
I find myself using 'join' a lot.