Planet gnome have started a trend…
$ history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
114 ping
107 sudo
82 ssh
71 top
71 cd
68 iwconfig
56 ls
46 usbkey.sh
43 ps
33 evolution
The output shows what commands you type the most, usbkey.sh is a script to unlock the secret-keys held on my usb key-fob, sudo is high up probably cause I use sudo to bounce services (the intel wireless drive crashes quite alot and both it and Network Manager then need restarting) and evolution needs a shutdown every now and again 
The other commands are fairly self-explanatory.
So what’s your history?
Here’s the history for my computer system, which runs Debian GNU/Linux 4.0 for AMD64.
131 cd
85 ls
50 aplaymidi
22 timidity
22 sfxload
19 mplayer
17 midload
12 gusload
11 su
8 sensors
“midload” is an alias I made which runs a command which I need to run many times in a day: “sfxload /etc/sounds/2gmgsmt.sf2 –volume=90″.