Seth Godin - Delivering on never
I will never leave a typo
I will never fail to warn you about a possible pitfall
I will never charge you more than the competition
I will never violate a confidence
I will never let you down
I will never be late for a meeting
There are lots of sorts of never you can deliver to a customer. You can't deliver all of them, of course. Picking your never and sticking with it is a fabulous way to position yourself.