Plink's recent campaigns with major retailers like Taco Bell and Burger King may provide a glimpse into what other new niche entrants can expect with their virtual currency loyalty programs. Consumers using Plink's three-month-old platform - which rewards retail purchases with Facebook Credits - are spending 65 percent more than before at participating brands while visiting twice a month instead of once, according to the technology firm.

American Express and Zynga today unveiled a similar loyalty card that lets consumers earn virtual currency.

Speaking with ClickZ on Tuesday, Plink CEO Peter Vogel shared aggregated data that was pulled from...