Since it seems like everyone else on Planet Mozilla is doing it… My twist: multiple systems. Actually I found it interesting too see the variation based on what I use them for.
Home
$ history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
114 ls
91 CD
63 sh
41 SSH
37 sudo
14 pico
13 exit
12 ping
10 ./gl_tail
8 top
Home Server
$ history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
68 ls
64 dig
55 CD
45 whois
27 ps
24 clear
23 sudo
14 pico
12 top
12 exit
Work
$ history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
67 top
65 SSH
31 ls
29 sudo
26 dig
23 CD
20 ps
19 svn
17 PHP
8 ping