When you've gotta go.
Overall, the applications we're most impressed with incorporate GPS technology. They give info suited to your exact location, so you never have to punch in zip codes or addresses. SitOrSquat (BlackBerry, iPhone, free) automatically points out nearby public restrooms and includes details such as whether they're open and if they have changing tables. It relies on user-submitted data, and some members even upload photos and rate toilets. But the selection is only as good as the local SitOrSquat community; pickings are slim if you stray from big cities in Europe, the U.S., New Zealand and Australia. A quirk: Many of the restrooms are at Starbucks — and really, how difficult is it to find a Starbucks?
When you're hungry and tired
- Restaurant-review sites Urbanspoon and Yelp (iPhone, free) both have apps that let you search based on your current location or a chosen neighborhood, price points or keywords like "vietnamese" or "fish tacos." If you can't make up your mind, try the iPhone's Shake function with Urbanspoon; a slot machine-like interface scrolls through restaurants that fit your criteria before landing on one randomly.
- Several hotel-booking applications we tried were disappointing, often turning up very few results in major cities. The exception was the one for hotels.com (iPhone, free), with which you can check out tons of hotel descriptions, ratings and prices; view properties on a map; and book with a tap of your finger.
- Some hotel companies are also in the game: The Choice Hotels Locator (iPhone, free), from the business that runs Comfort Inn and other brands, pulls up info and makes reservations at 5,800 of its properties worldwide.
Security measures
- Using Department of Justice data, iSafe (G1, $1) creates a safety profile of your location and a female voice alerts you when you enter a high-crime area. That's great in theory, but in our tests, iSafe went off at midday in safe Manhattan 'hoods like the Upper East Side. Bottom line: Don't underestimate old-fashioned street sense.
- Private-I (iPhone, $1) aims to retrieve stolen iPhones. For it to work, the thief must click on your phone's icon reading PRIVATE, which opens a screen that says "Accessing Pictures." It's a stall tactic so the app can e-mail you the phone's location. What next? Good question. Call the police, we guess, and hope the thief stays put.
Getting oriented anywhere
Based on your location, the Wikitude AR Travel Guide (G1, $1) shows nearby landmarks and popular attractions plotted on a map. Touch a spot on the screen — a museum, a bridge, a skyscraper — to read a Wikipedia entry about it or to view user-shared Panoramio photos of the attraction and the surrounding area.
Car trouble
- Culling info from 181 Web sites that track gas prices in the U.S. and Canada, Gas Buddy (iPhone, $3) lists what you'll pay for regular, premium and diesel at nearby gas stations, all shown on a map.
- Cheap Gas is a similar app that's free, but it has no interactive map feature.
- Trapster (BlackBerry, iPhone, free) warns of police speed traps — but even with thousands of user updates daily, the info can be old.
- The GPS-enabled ParkMark (G1, $2) remembers where you parked your car and guides you back via a compass-like arrow.
Passing time
- App games are a dime a dozen. Two of our faves are neat spins on travel-related classics. Plate Spotters (iPhone, $1) puts an end to the "are we there yet's" with an e-version of the license-plate game, in which players earn points for how many different states' plates they see.
- Meanwhile, The Oregon Trail (BlackBerry, from $5; iPhone, $6) updates an old-school video game. You travel virtually with a covered wagon, rationing provisions and deciding whether to hunt squirrels for food, pick up hitchhikers or get help when your kid falls ill with cholera.
- If you prefer to pass time by sleeping, there's a solution to napping past your destination. Turn on GPS-enabled iNap (iPhone, $1) and enter the address where you're going — and how many miles away from your destination you'd like to wake up. An alarm goes off when you reach the spot.
Staying in touch
A new app for making phone calls via Voice over Internet Protocol (VoIP) technology just might change the way you dial internationally, saving you a bundle in the process. The app for Skype (iPhone, free) functions similarly to how Skype works on the computer: Calling and instant-messaging other Skype users are free, and you pay as little as 2 cents a minute to dial a regular number. International calls cost next to nothing, and you can also receive incoming calls so long as the app is open. But you didn't really think they'd let Skype gouge AT&T's profits, did you? Making and receiving calls are only possible in Wi-Fi hotspots.
Communicating with the locals
- Get translations for hundreds of sentences and phrases — "red wine" in Italian, "nonsmoking section" in Mandarin — for 28 languages using the Lonely Planet Mobile Phrasebooks app (iPhone, $10 per language). Phrases are grouped into easily searchable categories like transport, banking and emergencies. Once you've found what you want, your phone shows a phonetic pronunciation and even reads it to you.
- A lazier option: Point It (iPhone, $5), an offshoot of the popular tourist book, consists of everyday travel images (markets, snorkeling, beer), with the idea that you display the appropriate photo to express yourself. Dorky? Yes. But handy if you can't get across that you need a Western-style toilet, or you don't want nuts in your food.
Finding a taxi when there are none
Plenty of apps pull up lists of local cab companies. Of all the competitors — including Cab4Me and Taxi! — we like Taxi Magic (BlackBerry, iPhone, free) best because of its Magic Booking feature. In over 30 cities, including Boston, Washington, D.C., and San Francisco, you can connect directly to a cab company's dispatch system and have a car sent to you, no phone call required.