Apparently, people have discovered that with a graphics program and color printer you too can print authentic-looking stamps for various loyalty cards. As a result, Subway, Cold Stone Creamery and others are eliminating these loyalty cards due to rampant fraud.

Wired News: Fraud Sinks Subway's Sub Club: Somebody told us you could buy our stamps on eBay, said Subway spokesman Kevin Kane. We didn't believe it. But sure enough, they were there.

Wired via c|net news.com