A terminal wrench for getting into control cabinets (apprently it's also called a hex can wrench). Sure, a nut driver is basically the same thing, but the terminal wrench looks better. And someday I'm sure I will need the small end for something.
For software tools, the best I can think of is VMware. My life got so much better when I started putting my old programs into virtual machines. Now I don't lose them all every time I wear about another computer.
