Smart Traveler
The official app from the U.S. Department of State intended for U.S. travelers, with updated country information, travel alerts and warnings, maps, and U.S. embassy locations. Check out the Know Before You Go section, which includes entry/exit requirements and safety info. You can also build itineraries and register for the Smart Traveler Enrollment Program with the app.
Free / iPhone, iPad

Lists food, services, and shopping at airports, plus wait times at security checkpoints. At press time, the app covered 100 airports in the U.S., Canada, and London.
Free / Android, iPhone, iPad, BlackBerry

Get notification of flight delays, cancellations, or gate changes, whether the app is on or off.
99 cents / iPhone, iPad, Android, BlackBerry

Language translation app. Text-to-text is free; text-to-speech is free for 14 days and can be extended with an in-app payment; speech-to-speech offers five free trials, then upgrade with an in-app payment.
iPhone, iPad, Android, BlackBerry

ICE 4 Travel
You may have an ICE (In Case of Emergency) contact on your phone. This app translates your information—medical conditions, contacts, allergies, medications—into seven languages (English, Spanish, German, French, Dutch, Italian, and Portuguese).
$2.99 / iPhone

Instapaper and Pocket (formerly Read It Later)
These two apps let you collect Web pages to look at later. So when you come across restaurant tips, insightful commentary, or must-see sight lists, you don’t have to print them out or try to remember where you found them.
Free / Phone, iPad, Android

Consolidates your itineraries and plans into one viewable schedule with extras such as weather forecasts and maps. Pro version offers enhanced services for travelers; Business version allows admins to manage itineraries.
iPhone, iPad, Android, BlackBerry

XE Currency Converter
Convert every world currency. It even works offline, using the most recently updated rates.
Free / iPhone, iPad, Android, BlackBerry

Frommer’s Day by Day
Super-rich content, but on the expensive side (as apps go), because you are buying an entire travel guide—and one that is interactive.
$9.99 to $14.99 / iPhone, iPad

Packing Pro
Use sample packing lists to create your own customized lists; keep track of what’s packed and what’s not. A master catalog has more than 400 items and to-do tasks.
Free / iPhone, iPad, Android, BlackBerry

Learn More: At the App Appeal Web site, you’ll find a continually updated list of the most popular travel apps.