"What's important?" is possibly the most powerful question in the coach's arsenal. It helps sort the wheat from the chaff, if you will. On a daily basis you've got clutter, both mental and physical, to contend with. There are people who are driving you just a little bit nuts with their incomprehensible behavior. And there are deadlines and expectations pressing you to move faster and more effectively. "What's important?" helps you put everything into perspective and take the longer term view.
As a time management tool
"What's important for you to accomplish right now?" In this segment of your day, what are the intermediate results that are going to get you closer to the ultimate outcome you're seeking? Is this phone call important, or is it only urgent - pulling at you but not related to results?
As a relationship manager
"What's important in your relationship?" How big a deal is it that your loved one throws wet towels on the floor? Is that more important than the fact that they care for you unconditionally? How important is it that they agree with your views on politics? Is it more important than their willingness to drop what they're doing and help you when you need it?
As a values clarification tool
"What's more important - buying a new car or having more money in your monthly cash flow?" For some people the answer is the car - for reasons of reliability, status, function, etc. For others cash in hand is king.
You don't have to be a certified coach to benefit from asking this question. "What's important?" helps you avoid breaking your legs jumping to conclusions about what other people think and feel. It works best, though, when you aren't invested in the other person's answer. Sometimes that's the hardest part.