These are usually boring but I liked the command line whoever originated the meme came up with.

~> history|awk '{a[$2]++} END{for(i in a){printf "%5d\t%s\n",a[i],i}}'|sort -rn|head 
   217	make
    58	gdb
    38	whois
    29	ssh
    28	python
    20	tools/symbrun
    19	hg
    18	less
    14	ls
    14	cd
 ~>  

Also, I like Charles Miller’s version.