Those are interesting ideas, and ones we kick around from time to time. In the past we've felt like other sites do this much better.
GasBuddy jumps to mind. They have people who report gas prices around the US and compile them into charts and maps.
Right now we're staying focused like a laser on personal fuel economy. Gas price reporting would require some new components like adding stations and locations. Another complication is that we have users across the world, and reporting gas prices everywhere has its own set of challenges. It's something we could build into the site, but we haven't made the decision to expand beyond our core mission yet. In the meantime, check out some of the other sites focused on gas prices.