A "suggested price"/"pay-what-you-like" sliding scale pricing system from an unlikely source:
Yoyo seems to think that all of my ideas end up in the mainstream before I can capitalize on them. I was originally inspired on the sliding scale pricing by this outfit: http://www.oneworldeverybodyeats.com/
After seeing that Panera is trying to do pay what you like, I'm more inclined to list a price and offer pay what you like as an alternative? As in, "This soda bread is $3.00 or PWYL."