In my area, gas prices have jumped beyond $4.00 per gallon over the last couple of weeks. I ranted before about how traffic lights contribute to decreased fuel economy. But I didn't mention that driving technique can dramatically influence fuel economy.
An extreme type of driving that maximizes fuel economy is called Hypermiling. Generally the idea is to minimize acceleration and braking. Unless you're going down a steep hill, acceleration requires more gasoline than just maintaining speed. And braking converts all your car's motion (which came from gasoline) into heat energy. So essentially, braking is like throwing away gasoline.
If this is the kind of topic that gives you goosebumps, you might be interested in the forums at CleanMPG, especially Wayne Gerdes' post "Beating the EPA - The Why’s and how to Hypermile".
And rather than boycotting gasoline for one day, folks should either not drive on that day, or at least drive more efficiently. With the subsequent drop in demand, gas prices would relax.