Apps to help with Travel Recordkeeping & Tasks
Gas & Fuel apps

Maps & Helpful Apps

There are all sorts of applications to provide maps for locations, so I'll just focus on a few that I've used.  You might want to check with some of the review sites or articles as to which will meet your needs.  

I use the iOS Maps app quite a bit.  It provides everything I might want, or almost everything.  I especially love it when I'm traveling and can watch the little blue dot move across and down the streets or highways to where I'm headed.  I find I use Maps to plot my route, to find out where I am and to find resources [hotels, restaurants, etc.] in an unfamiliar area.  Another alternative is MapQuest, which I haven't used much.  One nice feature is that it gives you buttons at the bottom of the screen to hit and find some basic catories of places.  However, since many seem to be copyrighted images [i.e. Holiday Inn's "H"] that's probably how MapQuest is paying for the app, which is free.

I also have CityMaps2Go which allows you to find maps to cities and regions in many countries [incl. the US] all over the world.  You need to have an internet connection to download them, but then they reside on your iOS device and you can use them offline.  You can also decide to pay $3 to get WikiPlus for your map, which will provide even more articles, lists of attractions, and images for your map.  This might prove quite useful if you want the information handy.  I did note, however, that the downloaded [free] map included "POI" [points of interest] which at least gives you some guidance before you choose to purchase WikiPlus.

A similar map app which allows offline access to information is 700CityMaps. The price is also $3 per map for offline reading and includes additional information for each map.

I just found AllTrails which is free and looks quite helpful for when you're hiking and trekking out in the countryside.  There are a number of other apps which will provide trail guides and park information [I have Chimani which focuses on national parks - and each of those detailed apps was free on Earth Day, when I downloaded them all!]