My latest app, TripCents, is now available. It lets you store a collection of named trips and calculates the approximate cost of gas, given the distance for each trip, your car's estimated gas mileage, and the current local cost of gas. I wrote it to help me gauge how much to budget for gas each month, and also to educate my kids as to how much money we actually spend shuttling them around town.
I'm particularly happy about the chance this gave me to flex some new iOS developer muscles. Where TreadCalc was essentially a single-screen app with no persistence, TripCents uses CoreData for persistence, has actual multi-page navigation and editable forms, and it renders its views using custom UITableViewCells. It also offers a lot of opportunity for incremental improvements, such as adding the ability to use Google's APIs for geocoding and directions, and MapKit to render geocoded destinations nicely.
You can read more about TripCents on my RuppWorks, LLC website, or if you just can't wait you can go straight to the store.