It really should be a fundamental business principle, but it's amazing how little attention it really gets. Occasionally we here about abysmal service (AOL, any outsourced phone support, etc), but rarely does good customer service get great exposure.
More often than not I'll bring lunch from home, but when I don't, my lunch stop of choice is the Quiznos down the street. Unlike other tech "areas" there aren't a lot of lunch eateries around the Gaithersburg office. I am also a creature of habit. Once I find something I like, I don't usually feel the need to order something different just for the sake of being different -- so I usually order the same sandwich (Cabo chicken, which they unfortunately just discontinued). After four years, the staff of this Quiznos know me. They know what I always order. Even if I'm in the back of the line before ordering, if they see me, they will go ahead and start making my sandwich before I get to the front. On more than one occasion, they have just given me the sandwich for free. I have no reason to go anywhere else and I enjoy going to lunch there. But it really makes a difference when you treat your frequent customers like that -- they will want to frequent your business.
At Duke, I had to regular delivery orders from La Fonte, an Italian restaurant in Durham. It got to the point that the phone operator recognized my voice and said 'hi' when I ordered. At the end of my senior year, the owner of La Fonte personally delivered one of my final orders and thanked me. I realize that this "above and beyond" mentality is actually harder to do and takes time and effort to accomplish right. As a regular customer, its easier to identify habits and personalities. But why don't more businesses take the time to treat their customers like they are already frequent customers? More than likely they will end up becoming frequent customers because of the service offered that isn't offered anywhere else.
I firmly believe great customer service is a key to any business. Getting your customers to love you and your product so they will become your own advocates. Why is this the exception rather than the rule? I know the "economic" reason is that it costs money and "hurts" your bottom line. Its a big red target when a company is looking to cut costs, but really it is like gutting your company. The people who interact with your customers, whether it is sales, marketing, or customer support, they are arguably your most important employees. Cutting that to help the bottom line, to me, makes no business sense.