Here are the commands I use most frequently. However I find lsof and pstree to be the most useful. Even if they are used infrequently.

  60 hg
  37 ./all.sh
  30 vi
  27 ssh
  27 ruby
  20 rm
  18 mate
  15 curl
  10 scp
  10 grep

can you show some examples of how you use them?

Well hg is the mercurial source control system. The ./all.sh is a script to go over all the projects (there are more than 30 active at this time) and check that they are you to date.

vi is an editor, as is mate (cli accesses to TextMate on the Macintosh). I tend to use vi when just editing a single file and TextMate when working on a project.

The ssh and scp are from deploying and managing projects to various machines. curl is used for testing that various REST apis are working correctly.

I never realised how much I deleted things :)

I love qalc. It's not really a command, but a command line application. It's a calculator with floating point arithmetic, knowledge of units (even exchange rates if downloaded) and some solving ability.

My top 10 commands is/are:

  201 ssh
  189 svn
   90 sudo
   84 rm
   73 ps
   70 qalc
   66 mplayer
   60 scp
   47 less
   46 cp

Interestingly, if I remove the ls and cd removal, ls comes in at only the fourth spot. (cd comes at the no. 1 spot, unsurprisingly.)

P.S. I had to change the $2 in the awk command to $4, since I store dates with the commands.