Before the trip
FIND FLIGHTS Kayak's website set the standard for streamlined searching, and its app delivers the same ease-of-use on the go. Simply enter your destination and travel dates, and the app spits back options sorted by price, time, or airline; a single click takes you to the corresponding booking site. Free.
SCOPE OUT A HOTEL With thousands of user-generated reviews of hotels, restaurants, and attractions worldwide, TripAdvisor has long been a mother lode of unvarnished assessments. What it hasn't been is a model of simplicity. The app cuts through the clutter, bringing just the facts—er, opinions—filtered by price or neighborhood, to the fore. Free.
TRACK YOUR ITINERARY Forget paging through printouts of confirmation codes and terminal info. The TripIt app culls flight numbers, gate information, and even loyalty-program account numbers from e-mail receipts you forward. From these, it assembles a master trip itinerary you can access from anywhere. Free.
EXPLORE YOUR OPTIONS Lonely Planet has created the perfect pairing of inspiration and information. First, flip through the colorful, photo-heavy 1000 Ultimate Experiences iPad app for thumbnail takes on some of the world's most intriguing destinations. Then use the brand's dedicated guides (for nearly 58 cities) to hunt for specifics, like how to get a bus pass for the MUNI in San Francisco or when to catch the ferry for a visit to Alcatraz. 1000 Ultimate Experiences $4, San Francisco travel guide free, other city guides $6.
SCORE A CHEAP ROOM If landing a rock-bottom rate ranks higher than remaining in complete control over where you stay, roll the dice with Priceline's Hotel Negotiator app. You choose a preferred star rating and an ideal price (recent successful bids in the area are listed as a guide), and the tool will lock in a room that meets your criteria. Bonus: The app uses GPS, which is priceless for lining up convenient last-minute accommodations for unexpected overnighters. Free.
GET A BIRD'S-EYE VIEW You've probably already used Google Earth's satellite images to zoom in on your childhood home or your current residence—in almost scary detail—but the intuitive app also serves as an easy way to suss out a hotel's rooftop pool deck or the size and location of various parking lots at a big museum or other attraction. Free.
MAKE THE MOST OF A LAYOVER Consider it Yelp for airports. GateGuru's app contains searchable directories for 92 U.S. airports and more than a dozen international hubs. They take the guesswork out of finding an ATM, a decent cup of coffee, or a 10-minute massage station—wherever you happen to be delayed. Some locations even have user reviews, rankings, and photos. Free.
CRAFT A CONTINGENCY PLAN For the frequent flier who has no time for snafus, FlightTrack Pro is an essential aid. In addition to storing and tracking your flights, it pulls vital info like gate changes and weather reports for 5,000 airports and 1,400 airlines. If your flight is canceled or delayed, it's easy to search for other connections while you're standing in line for the gate agent, or even from 30,000 feet—you can access the app's route-maps feature offline when you're in the air. $10.
KILL TIME IN THE TERMINAL First, give yourself some elbow room. Then fire up Scoops, a highly addictive game even a technophobe could master. Your only goal is to position a virtual ice cream cone under colorful scoops that fall from the sky, using the phone's motion-sensitive accelerometer to direct the cone with a tilt of the wrist. Free.
KILL TIME ON THE FLIGHT The perfect nervous-passenger distraction, Flight Control HD for iPad gives folks something to focus on while surviving a long-haul flight: an air-traffic-control strategy game that lets you manage planes' flight patterns by dragging them along the touch screen. If only getting to your real-world destination were so easy. $5.
ENTERTAIN THE KIDS IN THE BACKSEAT Dr. Seuss goes digital with iPhone- and iPad-ready versions of his best-selling stories. Let The Lorax app be your on-the-road babysitter: It reads the story aloud, and when you tap an illustration, the machine will speak its name ("Trees." "Grass." "Pond."). $4.
On the ground
LOOK LIKE A LOCAL Because some things just require visuals, Howcast's user-generated video tutorials cover everything from taxi strategies in New York City to the proper consumption of soba in Japan to nude-beach etiquette. (Then again, maybe some things don't belong in a video.) The short clips load quickly and particularly shine on the larger-format iPad. Free.
SURVIVE WITHOUT A PLAN So the museum you planned to visit was closed, and now you've got a free afternoon on your hands. Goby has you covered: The app searches events and activities near you—live-music shows, family-friendly outings, and outdoorsy pursuits—and plots them on a map with details and photos. Free.
RUB ELBOWS WITH REGULARS It's no easy feat to cut through the restaurant-of-the-moment hype in an unfamiliar city, which is where the no-holds-barred user reviews on Yelp's app come in. Using your GPS-mapped location, the app reveals the highest-rated places near you, as determined by the people who know best. Search thousands of dining options in the U.S., Canada, the U.K., and Ireland by price, neighborhood, or the handy "what's open now." Free.
SNIFF OUT CRITICS' FAVORITES If you're more interested in getting a recommendation on the spot, download Urbanspoon. The app makes a game of finding a restaurant: Search options are displayed slot-machine style, with neighborhood, cuisine, and price as the categories. Refresh with a simple shake of the device, or click off for critics' reviews and some menus. Bonus points for the spanking-new iPad format. Free.
MAKE DINNER RESERVATIONS Instead of calling 12 restaurants to find one that can seat your party of four, let OpenTable do the work. Search more than 13,000 restaurants in Canada, the U.K., and the U.S. by the number of diners and your desired reservation time, and then sort by cuisine, price range and neighborhood. And in about five taps—voilá!—you've got a reservation. Free.
SIP SMARTER With more than 750,000 bottles of wine from Chile to Cali cataloged, the Cor.kz app is like a pocket sommelier. Search by region or varietal, peruse an exhaustive glossary, or scan a bottle's bar code with your smartphone to call up expert ratings and tasting notes. $4.
GET THE SHORTEST LINES AT DISNEY The Undercover Tourist app is the savvy best friend of any Walt Disney World visitor, delivering accurate wait times for every ride in the Magic Kingdom, Epcot, Disney's Hollywood Studios, and Disney's Animal Kingdom. At day's end, a built-in GPS helps you navigate back to your car. $4.
MAKE SENSE OF YOUR MONEY For up-to-the minute currency conversions, try ACTCurrency. It lists more than 190 exchange rates, updated with every tap of the refresh button. Tip: Turn off the auto-update feature while you're abroad to avoid sky-high roaming charges. $1.
SPEAK FOR YOURSELF Overcome awkward lost-in-translation moments with World Nomads. The 25-language translator app covers keywords such as please and thank you, numbers up to 10, and a few phrases useful for other travel conundrums (our favorite: "Those drugs aren't mine!") in easy-to-scan categories like Introductions and Travel Health. Most phrases have audio clips. Free.
FIND A PLACE TO "GO" Like it or not, Starbucks outposts have unofficially replaced service stations as America's favorite rest stops. Fortunately for travelers, both are mapped on the SitOrSquat app. More than 92,000 restrooms are represented (concentrated in larger cities in the U.S. and Europe), with details like hours, changing-table availability, and, of course, a "sit" or "squat" recommendation. Free.
SEND A PERSONALIZED POSTCARD Nothing says "wish you were here" like a good old-fashioned postcard—with your face smack in the center. For about $1 per note, HazelMail turns your photo into an actual paper card complete with a custom message and then stamps it and sends it off within about two business days, saving you the trouble of hunting down a local post office. Free.
DOCUMENT YOUR ADVENTURES It may have been invented for students, but Facebook's ubiquitous app has become an invaluable tool for all kinds of folks. Travelers can share crazy vacation moments on the spot, either in the live feed of status updates or in a mobile gallery where they can instantly dump cell phone pictures. Free.
FAKE PERFECT PHOTOS Fancy effects can turn even the most amateur photos into works of art. Use Photogene for iPad to add background colors, crop out mistakes, or just remove red-eye from that otherwise-flawless family portrait in front of the Eiffel Tower. $4, iPhone version $2.