coupon Though they are not yet widely promoted, marketers are starting to see the benefit of offering digital coupons. Since consumers can easily access them via mobile devices — at home or on the go—digital coupons have the potential to influence a consumer in the midst of a purchase decision.

“When the economy goes down, people tend to find ways to save money,” said Gordon Borrell, CEO of Borrell Associates. “It’s also that the proximity of the mobile device to someone’s wallet is a heck of a lot closer than a PC when you’re out driving around.”

eMarketer estimates that nearly 20 million U.S. adults will redeem a mobile coupon this year and that mobile coupon usage will double by 2013. “Even as the sputtering economy attempts its recovery, the popularity of couponing has continued,” said Noah Elkin, eMarketer principal. According to Elkin, the appeal of mobile coupons among shoppers is broadening the usage and acceptance of digital coupons.

One of the challenges marketers face is learning how to promote and effectively leverage mobile coupon programs. And, although mobile coupon usage continues to rise, most consumers have yet to be convinced that using their mobile devices as a payment mechanism is beneficial.

“Consumers already use phones for online payments,” says Josh Peirez, MasterCard Worldwide’s chief innovation officer, referring to downloaded songs and software. “The goal is to get them comfortable doing the same thing in the physical world.”

It’s already happening. This year, eBay expects U.S. consumers to buy $1.5 billion worth of goods using its smartphone apps. And PayPal already lets users send money via text message. Osama Bedier, PayPal’s VP of mobile platforms and new ventures, envisions a service that stores gift cards and sends alerts when the consumer is near a merchant. U.S. Bank is currently developing a location-based app that can offer instant coupons —a shampoo discount to shoppers browsing the hair-care aisle, for instance.

Are you planning to launch a mobile coupon campaign this year? If so, what kind? If you’re sending coupons to your email list already, can they be redeemed from a mobile device, either in-store or online? We’d love to hear your feedback.