Mapquest is offering a new fuel locating (and pricing) tool. Its easy to use by pulling down the type of fuel (ie. biodiesel) and although not as functional (IMHO) as those independent "mash-ups" using GoogleMaps. It also looks to be competing in the 'watching fuel prices' kind of sites by offering price updates although needs to develop its network of 'watchers.' Check it out if you are looking for station locations on your next trip or just around town. (add missing stations by clicking the 'help' link. I recently added the Lebanon, Ohio )

Clean Fuels Ohio maintains a good up-to-date list of stations in Ohio ... it a good source to check, and utilized an excellent Yahoo map from the link at the top of their page.