Code promotions, like so many other traditional marketing tactics, are being transformed by the web.

Code-centric promotions, a mainstay of Madison Avenue, go back to the 1930's, and major marketers like Cadbury Schweppes, Coca-Cola, DaimlerChrysler, Hershey and PepsiCo are still sponsoring elaborate campaigns centered on promotional codes, which are redeemable for prizes or for entry into sweepstakes. But consumers now redeem codes by going online, to dedicated websites, writes the New York Times.

Once consumers reach those sites, marketers can offer more promotions, ads and offers - and collect email addresses and demographic information. Moreover, mobile campaigns now allow consumers to enter codes by sending cellphone text messages.

"The idea of logging in every day to see if you've won takes codes beyond simple proof-of-purchase promotions," marketing consultant Joseph Jaffe, author of "Life After the 30-Second Spot," is quoted as saying. "The codes of yesterday were a foot in the door for marketers. Now they're substantive branding tools, encouraging full-blown relationships."