A well-stocked smartphone is nearly as essential as a passport.
Courtesy of Travel App Box
Travel App Box
You could download a dozen similar apps and still not match the functionality that Travel App Box offers. Billed as the Swiss Army knife of travel apps, it is a flight tracker, currency converter, tip calculator and many other useful tools rolled into one package. It also features offline maps—including public transportation layouts in 40 cities worldwide—for when you are stuck somewhere without cellular or WiFi service. For iOS; $1.99.