I'm mostly participating in this particular thing because it seems to have changed since I tried this last. For one thing, ikiwiki didn't exist last time I tried it, also I don't remember seeing svn on the list last time.

joey@kodama:~>history 1|awk '{print $2}'|awk 'BEGIN {FS="|"} {print $1}'|sort|uniq -c | sort -r |head -10 
    229 l
    129 cd
    126 e
     48 mutt
     43 fg
     42 svn
     40 w
     26 ..
     24 ./ikiwiki.pl
     22 build

I use zsh, so this summarises several thousand lines of history shared amoung all my zsh sessions, and also .. is used to go up a directory. l is my shorthand for ls; e is my shorthand for "vim or the closest available substitute"; w is mostly a nervous habit since this is a single user machine -- my hands tend to type w and ls at the terminal when my mind is off working on something; build is my dpkg-buildpackage wrapper.