Google Maps
Google Maps is without a doubt one of the best travel resources available out there. Unless you are using it for commercial applications its also free, so there is no reason not to have this on your phone.
From within the app or on your computer you are able to look up places of interest, a restaurant or a store that interests you. You can check reviews, get directions or just see traffic and travel times.
If you are going to be in a new place where you may not have data for your phone you can even download a regional map of the area so that you can use some of the basic features even while you are offline. Your phone can still use the free GPS service with the map information already downloaded on your phone to help get you to and from where you want to go. This can be extremely helpful if you have run out of data, or don’t plan to buy any wherever you visit.
In addition to its amazing map service you can get information on the places you want to go. Other people will post photos and reviews so you can see first hand what the place is like and if it is worth your time to visit. There does not seem to be a huge amount of fake reviews, and for the most part I’ve found that the 2, 3 and 4 star reviews as well as the more detailed 1 and 5 star reviews are usually genuine. Using the feedback and reviews from other people has saved me from going to a number of bad places.
If for some reason you do not have this free app on your phone use the links at the top of the page to grab a copy before your next travel adventure.