guillermo@guillermo-laptop:~$ uname -a && history|awk '{a[$2]++ } END{for(i in a){print a[i] " " i}}'|sort -rn|head
Linux guillermo-laptop 2.6.22-14-generic #1 SMP Tue Feb 12 07:42:25 UTC 2008 i686 GNU/Linux
139 cd
62 cvs
44 sudo
40 run-mt.sh
33 java
20 exit
15 dir
10 cvs-moz.sh
7 ./a.out
6 wget

A Meme from planet.mozilla.org.

http://www.ardisson.org/afkar/2008/04/15/counting-commands/

http://coop.deadsquid.com/?p=1084

http://weblogs.mozillazine.org/bz/archives/019205.html

http://ventnorsblog.blogspot.com/2008/04/such-strange-meme.html

http://benjamin.smedbergs.us/blog/2008-04-15/history-meme/

http://dougt.wordpress.com/2008/04/15/scratchbox-history-6/

http://www.bitstampede.com/2008/04/15/nerdiness-survey/

… and a lot more!