If you're smart, you understand the power assistants hold.

Melba J. Duncan, for instance, once stopped a plane. The former executive assistant to Pete Peterson, former CEO of Lehman Brothers, Duncan says people often don't give people like her enough credit. Assistants succeed and become an asset to their bosses because they're not limited to their job description. Other employees, however, often misunderstand what exactly assistants do. 

Duncan now runs the Duncan Group, a consulting company that recruits, coaches and trains assistants. She says the good ones are adept at a delicate skill all employees should master.

It's called "managing up."

Duncan says employees can underestimate the skills, judgment and influence of executive assistants. Everyone in the office can benefit from taking a moment to pay attention to how effective assistants communicate with and manage the corporate bosses.

And if you're the boss, and you want to know what kind of people work for you, watch how they treat your executive assistant.