Without spending a dime, yet you can fight cancer, help at-risk girls, prevent child abuse, offset carbon emissions, battle poverty, deliver vaccines, donate a book, plant a tree and feed a chimp.

Shopkick, creator of the CauseWorld app, declined to disclose the dollar value of each karma point. However, CauseWorld users have collectively raised hundreds of thousands of dollars so far. "We're donating at a rate of $200,000 a month," says Cyriac Roeding, CEO of Shopkick, which charges a 20 percent handling fee.

The money comes out of the marketing budgets of Procter & Gamble, Citi and Kraft Foods, which sponsor the program. Citi alone has already donated $700,000 on behalf of CauseWorld users. More than 325,000 people have downloaded the app since its debut in December last year.

"Two GlobalGiving partner projects have already received over $20,000 each," says Donna Callejon, chief business officer at GlobalGiving. "The funds generated by CauseWorld will provide over 100,000 pounds of oranges, a staple of nourishment for rescued chimps at the Jane Goodall Institute in the Congo. And in Sudan, thousands of refugees will have access to clean water."

Yet the plight of refugees in third-world countries seems utterly distant as I saunter down Main Street-until, of course, I call up CauseWorld. The app quickly gives me a list of nearby shops and restaurants based on my GPS location. I'm allowed 10 check-ins every 24 hours with a minimum of three minutes between each check-in. A check-in earns you five karma points.