Newbie’s Top Ten Commands: If you find yourself working at a *inx command line more than you like, and you have little idea what to do, this is a great resource. The information in this document will at least let you get around and look like less of a goon.
It’s well-written, though I would have included top and kill, since those are handy if you’re administering a system and something goes wrong.
Here’s another good list, though they have 12 commands, including fundamentals like cd, mkdir, and rm.
And, finally, another top ten list with some obvious ones like mv and cp.