Google Maps is a great app - I'm sure you've used it at least once. Now, it's been updated with cool new features, including offline maps.
Going on a big trip? Find your route and then "Save map to use offline" - that way, you won't be disconnected when you're out of range of your service plan or Wi-Fi.
Another new feature now shows you which lane to stay in or move to so you can be ready for your next turn or exit. Alternate routes will show up more easily also.
You can also plan out public transit and get times for your routes.
It still has its best classic features, too, like Street View, turn-by-turn directions, and more.