If you aren't already using it, Gas Buddy is a great phone app you can use on iPad, too, for finding fuel locations and their recent prices. Has saved us many $$$$. It works because users all over the country take a few seconds and update the price whenever and wherever they fuel up.
I like Weatherbug for checking conditions. You can enter the name of the next town you can to stop and view the forecast, see radar. Quicker than some of the fancier weather apps.
You can also easily create your own apps ( on iPad, assuming same is true with yours.). If you have a favorite web site like a forum that you view often, just click the box with an arrow at the top of the screen. Press "add to home screen" and you have your own app to go there instantly.