I prefer curl'ing icanhazip.com, and I make it a quick alias in my .bashrc:

    alias myip="curl icanhazip.com"

Apachebench (ab) is a decent alternative to siege, and knowing how to use tcpdump and netcat comes in handy for debugging. Other than that, my new favorite command line tool over the past several months has to be vagrant, which lets you script and streamline VM creation and builds from the command line. If I need to completely reproduce my production environment on a test box, it's my utility of choice.