Apple has just updated its maps software with cute photo-realistic 3D representations of buildings in some central city locations.

London - Your smartphone remains a crucial travel companion: currency converters with the latest rates, Skype to make calls home, ebook readers to keep you amused. But travel apps offer much more. There are lots of them - 49,000 on the iPhone alone. Here are a few you shouldn't be without.

Electronic boarding passes save you scrabbling for pieces of paper. The British Airways app (iPhone, Android, Windows Phone, BlackBerry; free) is one of the best around. It's simple and informative. But now there's a new app which comes built in to the iPhone called Passbook (iPhone, free). It gathers together your store cards, money-off coupons, concert tickets and boarding passes in one place. United and Delta are signed up already and more airlines will join. The neatest thing is that when you get to the airport, the phone's GPS knows this and automatically loads the boarding pass onscreen.

Once abroad, you'll need to find your way around. Apple has just updated its maps software with cute photo-realistic 3D representations of buildings in some central city locations. However, you need a data connection to make it work and overseas roaming costs add up fast. The new version of Nokia Maps, out next month on Nokia's latest Windows Phone handsets, allows you to download country maps in advance and offers turn-by-turn navigation without data.

If you don't speak the lingo where you're going, you'll need help. There are plenty of good apps, but the best is Google Translate (iPhone, Android; free). Again, you'll need to have a data connection for this. Speak into the phone: your words go to Google's servers to be translated into one of 64 languages, then show up as translated text onscreen; most are also relayed as spoken words. A conversation mode means that it knows to listen to the other party in Spanish, say, and translate to English. Slightly magical.

If you're in New York, one of the coolest apps is New York Nearest Subway (iPhone). It uses AR (augmented reality), where the view from the phone's camera is supplemented onscreen by extra information. Hold the phone in front of you and colour-coded signs appear to float in the air, pointing to the nearest station. There are now companion apps for lots of cities, including Paris, London, Barcelona, Chicago and Tokyo.

Among apps that provide useful information without data charges are travel guides, including TripAdvisor Offline City Guides (iPhone, Android; free). There are more than 50 cities, with maps, photos, tourist attractions, restaurants and more, plus TripAdvisor reviews. Rather than putting the whole thing on your phone, choose cities to download before you travel.

While you're away, send a postcard home using Touchnote Postcards (iPhone, iPad, Android; free). Take a photo on the phone, choose the recipient's address, write your message and it's done. It'll be delivered on glossy card to an address anywhere in the world.

Finally, keep the kids happy with Barefoot World Atlas (iPad, iPhone), an interactive 3D globe with clever graphics that illuminate wildlife, landmarks and shipping vessels, along with interesting country stats. - The Independent on Sunday