Well, not quite free, but while we're on the subject of cool websites, another one to check out is GasPriceWatch.com. There are a number of gas pricing sites popping up on the web but I've found this one to be both fairly comprehensive and easy to use. It's a peer contributor website, where "spotters" (and anyone can be a spotter) input gas prices they have seen around the nation.
You simply put in your address or area of interest and you will get reports of gas prices in your area, color coded to indicate how recently the prices have been updated. It couldn't be easier, and the only way we're going to get these gas prices down is by consistently going to the cheapest pumps, so let's get cracking.