A gas station that charges a random amount for gas, ranging from 50 cents below the market price to 70 cents above. So in Columbia, where gas is currently $2.79, prices would range from $2.29 to $3.49. On average, the station would make more money, but people would line up, hoping to get the lower price. You could even put a slot machine style lever on the side of the pump.
I know, I know. There are problems with it. People would buy less gas if they pulled the lever and got a higher price. There could be violence. And it's probably illegal. And definitely evil.
But I think there are important business lessons to be learned from the casinos. With that in mind, you could also make it really hard to find the exit of the gas station, so that people have to drive around so much looking for it that they need to buy more gas. Or is that taking it too far?