Hmmm, is this HN worthy? These commands are so basic that I don't expect any HN-reader using Unix systems not to know those.
What about some slightly less basic ones that I'd think would be useful for many people.
# less with syntax highlighting
alias less="/usr/share/vim/vimcurrent/macros/less.sh"
tailf # tail -f, but better & shorter
mtr # check your connection (ie., traceroute with more info)
htop # nice a colorful process listing (better than top)
locate # search files by name -- that late-night disk thrashing is useful after all!
I ask the programmers on my team, some of whom are quite junior and unexperienced, to send weekly status reports with an overview of what they did in the previous week, what they expect to do in the next, and other. Other is usually made up of areas of concern and interesting things that have made it onto one's radar. (You can put basically whatever you like in the other section. I'm still hoping somebody will send a joke.)
Since I wouldn't ever ask them to do something I wouldn't do myself, I send these reports too. This link will go in my miscellany section this week. I think it'll be useful, and I wouldn't have ever found it or even considered including something like it had it not shown up on HN.
Because the vim macro changes all settings so it behaves just like less, including making the file effectively read-only, and without the overhead of loading all the plugins.
What about some slightly less basic ones that I'd think would be useful for many people.