A basic premise in economics is that markets are more efficient when both parties have similar information. This allows competition to work and for the market to reach an efficient match of quantity supplied and quantity demanded. Now, rightly or wrongly, many people assume that the supplier or seller is generally presumed to have superior knowledge. One can argue whether or not this is a valid assumption, but I'm going to go with it for purposes of this post.
If the supplier does have superior information, then a tool that provides the demander or consumer with more information about the market should make for better competition a more efficient market. Such a tool can be seen at this site.
The site collects gasoline price information from volunteers around the nation and provides recent gasoline prices to help consumers determine where the "best" price might be. The most interesting portion is "below the fold" in the left hand column of the site. It's the gasoline temperature map and compares average gasoline prices, by county, across the nation. You can zero in and even find information by city or zip code. I've browsed around and the information is by no means complete. Outside of larger metropolitan areas, the information seems spotty at best, and totally absent in many cases. Nevertheless, it might be an interesting tool to demonstrate with your economics classes when discussing the value of information in the local market. It could also be used when teaching comparative shopping in a personal finance or consumer education course.
I've got a family road trip coming up this summer. I might even put it to the test.
I'd be interested in your thoughts about this as a teaching tool, and if you're a contributor to the site.