Call me a dork, but if I get good service somewhere, I will hop online and comment about it.
If you managed to get through your teen/college years without working in some form of customer service, good for you! You're either independently wealthy or you discovered some other crafty way to make your bucks.
For me, I did 11 years of hard time in retail. Within the first few months at my first job, they figured out that I had a brain and that I was way too straight and narrow to even think about breaking the rules. Because of this, they gave me store keys and at 17, I was promoted to "junior assistant manager," which sounds silly, but it opened the door to retail management for me for the next decade. I was actually pretty successful.
I worked for a number of companies and eventually started "trouble shooting," which means a company would contact you to convince you to take over the crappiest store in their district, which usually meant theft (internal and/or external), bad sales, corrupt staff and inventory issues. My job was to go in, get the right staff in there, clean it up and start making money. I did that and loved it. Within 8 months, I could make even the worst hell-hole profitable, and I did it a number of times for three different companies.
In that time, I met a lot of outstanding people. Really nice students who were working hard to make money for school, moms who just wanted to get out of the house and plenty of folks who just wanted to work a few hours to get the discount. I worked hard to find the right combination of great people to better each store. And they worked hard. Magic. For not much money. I treated them like gold, though...worked around their schedules, listened, tried to make it a good, encouraging environment.
When I look back on my retail career, it's not the long hours, blisters, rude upper management, or low pay for myself that darkens my memories. It's sitting down at review time with someone - who has worked like mad to make the most of a rundown store, stood for hours ringing customers and smiling all the way, who vaccumed and Windexed obsessively to make the place presentable, who folded sweaters or hung new clothes for hours on end - and give them a fantastic evaluation, and then only be able to give them a five or ten cent raise to go with it. Darned corporate bastards! There was never any budget for rewards.
Granted, this was ten years ago, but I know that things haven't changed that much.
So! If you are in a store and the associate there is helpful and polite and smiles and does a good job...if he isn't leaning on the counter looking bored before you walk up...if she is busy doing something but not too busy to help you...get their name off that receipt and get online and take a few minutes to give them a thumbs up. Really. It can help them get a better increase or promotion, and even if it doesn't do that, at least it will make them feel better about their hard work.
After all, there is a lot to be said for putting the spring in someone's step, right? It will make you feel good, too.