Can Amazon.com help us become a more generous country?

You might have missed it during Black Friday’s race (or rather, stampede) to the bottom, with gunshots, tramplings, and arrests abounding across the country. But at the same time that galloping herds were charging towards low-priced flat screens, the online retailer Amazon was quietly pinging our inboxes with quite an announcement. Starting this week, any Amazon customer can select the charity of his or her choosing, and Amazon will automatically donate 0.5 percent of the customer’s purchases to a worthy cause. The program is called “AmazonSmile,” and if taken to its extremes, it has the potential to subtly shift the contours of American giving.

It’s pretty remarkable. Every time you log in to buy a new blade for your Magic Bullet, Amazon will, at its expense, chip in a portion of the price to a cause you love. Almost every item is eligible—from Playstation games to pots and pans—including deeply discounted items and stock listed on Amazon Prime.

The whole process is surprisingly easy. I visited smile.amazon.com and selected a favorite charity (mine was “Life Pieces to Masterpieces”, a wonderful organization in Washington that helps at-risk young men turn their lives around through art). I then proceeded to purchase the third novel in the Hunger Games trilogy (don’t judge me: that cliffhanger Katniss left us with in the latest movie was beyond unbearable). And—poof!—good deed done.

Half a percent per item may not seem like much, but extrapolated across the entire universe of Amazon users, it’s more than noteworthy. Consider that Amazon has about 164 million annual users, with an average value per user of around $543. If every Amazon customer took the simple step of signing up for Smile, they’d contribute over $400 million extra dollars to charity each year.

And what if the effect cascades beyond Amazon? If Smile proves popular with consumers, it’s only a matter of time before other e-tailers get in the game. I for one am much more likely to hang on to my Hulu subscription, or finally dive behind the New York Times paywall, if I can help out my favorite nonprofits at the same time. I imagine lots of others would say the same.

With Smile, Amazon joins the growing roster of corporations willing to sacrifice a slice of their bottom line for the greater good. I’d include those patriotic retailers who refused to open their doors on Thanksgiving on this list, along with these big-fish givers who pushed through the economic downturn and still ponied up for charity.

But in some ways Smile goes beyond corporate philanthropy: call it “embedded giving,” benevolence woven into the very fabric of the marketplace. Here’s hoping other companies follow Amazon’s lead. It would take some of the black eye off of Black Friday, and help millions of vulnerable folks around the country with the click of a mouse.