History Meme
Alright, I'll play.
psanford@korah:~% uname -a
Linux korah 2.6.24-16-generic #1 SMP Thu Apr 10 12:47:45 UTC 2008 x86_64 GNU/Linux
psanford@korah:~% history -1000 | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
203 ls
192 cd
62 fetchmail
54 ssh
31 ruby
31 rm
31 git
30 firefox
28 svn
17 irb
(My shell is zsh)