I had two interactions that have turned me into a raving fan and it was simple, small, effective and cost the companies, probably, next to nothing.
Upon suspending my Montreal Gazette subscription for a fistful of days while I head off to NYC the very kind and professional customer service rep asked if I "would like to have my copies of the Montreal Gazette donated?" - brilliant! Heck, I'm not going to use them, the Gazette probably tosses away tons of copies but the thought of mine being donated to someone feels damn good. That one questions adds weight and integrity... and it's as simple (and brilliant) as "would you like fries with that?" Let's be honest they can donate them and not tell me, but the act of asking is powerful and works.
Secondly, on a recent stop at a Couche-Tard (Quebec's answer to 7-11) the cashier asked me if I would like to add $0.25 to my bill and that money would go to a local charity that helps children. I stopped, thought about and said "add $5" (still an embarrassingly pittance). I then began thinking: "how many people would say 'no' to twenty-five cents being added to their bill?" Then I realized how quickly those quarters can add up. Another win-win: the company raises big bucks for charity, creates awareness, becomes better community citizens and helps me help out a group I may not have had awareness of. I know where I'm stopping the next time I need a fix of Shrek 2 M&Ms or some Doritos.
Final point: it's easy to build your brand by doing simple, low-cost acts of kindness. It's the small stuff that leaves big impressions.