Panera Bread is trying the Pay-What-You-Want method at one of their outlets in St. Louis, Missouri. Patrons are asked to leave money in lockboxes in lieu of paying cashiers.
The New York Times reports that the same experiment is being tried be around a dozen companies around the country. Their reporting shows quite a bit of difficulty when the concept is put into practice.
Fixed to Flexible – My ebook on pricing where we talk a bit about PWYW.