Now I'll admit that I don't do much driving nowadays because I use mass transit (i.e. the subway), but I did drive a lot once upon a time. And it was quite the pain to deal with all of the extraneous annoyances like traffic, insurance, and gas. Guess which of those problems Gas Logs addresses?
The latest app from JAS Appications allows users to track their mileage, their spending, etc... All manner of values can be adjusted to fit a user's region, including gallons/liters, and a number of different currencies. Of course, it just wouldn't be a JAS Applications app if it didn't also include a super-useful GPS feature. Which it does. Yup, as expected Gas Logs can do all this in addition to finding nearby gas stations by using the iOS device's built-in GPS.
Again, someone like myself who doesn't even own a car won't have much use for it but there are billions of people out there who drive, and at least millions who own an iPhone. Chances are good that there's a decent market for something like this.