Gasbuddy is one of many gas station price trackers on the Market, but consistently has the best prices of all the apps I check.
GasBuddy works like most of the other price-finding apps out there. Either enter a zip code of where you want to find gas or choose "Find Gas Near Me." From there, GasBuddy will give you a list of gas stations and their associated gas prices. By default, the stations are listed closest to furthest, but you can also sort them by price.
From the tabs at the top of the page, you can cycle through the prices for regular, mid-grade, premium, and diesel. You can also move off of the list view and switch to map view, which puts the logos of the stations on a Google Map with the price of gas below the logo.
GasBuddy manages to always have the most up-to-date gas prices by giving away points to registered members for updating gas prices when they're at the station. For every 1000 points you earn, you can enter yourself in a drawing for a $250 gas card. As a result, most of your results won't be more than a few hours hold when you check the stations around you.
The settings menu is rather bare, because there's not much in ways of customizing GasBuddy. On the settings menu you've got options to choose your default fuel grade, distance (miles or kilometers), showing all stations or just those with updated prices, and setting the default screen the app opens up to (home or stations near me).
If you're into saving money (and who isn't?), GasBuddy is an essential app for your phone. Even if you rarely use it, you'll be glad to have it when the tank is nearing the dreaded E. GasBuddy is a free app that seems to occasionally pop up an ad, but honestly, I haven't seen an ad until I decided to review the app right now. Even then, I'll take a rarely seen (and easily avoidable) ad if it means saving at the pump.
More pictures and download links are after the break.