Here are my top ten: d l m o ll e pwd rm dict open.

d <foo> is short for {cd <foo>;ls}. l is ls. m is mv. o is Apple's open command. e is emacsclient.

The only reason grep is not in that list is that I do my grepping through an emacs command (M-x grep).

pwd is frequent because I do not put the working directory in my shell prompt.