Tripit and Triposo are great examples of useful travel apps that don't need data or internet access.
"Tripit is a fantastic place to store your itineraries and travel confirmations, and Triposo provides crowd-sourced data to help travelers find the best shopping, drinking, and dining suggestions in many destinations," says Bisesto. Google Maps can also be used offline as long as location services are turned on; users can see the blue dot signifying their location almost anywhere.