GasBuddy.com

"GasBuddy.com can help you find cheap gas prices in your city. It
is comprised of 170 gas price information web sites that help
consumers find low gasoline prices." Search for prices by ZIP
code. Information is member-supplied. Registration (free) required
to post gas prices on most of the gas sites or to create a fuel
log for tracking your expenses. Includes tips for conserving gas,
links to news stories, and other resources.