Country? City? Culture? There's an app for that

The mobile phone's days as a phone didn't last long. Ericsson announced last week that mobile data traffic passed voice traffic worldwide at the end of 2009. Stacey Higginbotham wrote on the GigaOM blog: "Worryingly, that data traffic was generated by an estimated 400 million smartphones set against 4.6 billion mobile subscribers making voice calls. What happens when everyone has a smartphone?"

Good question. While we're waiting for an answer, let's look at what's behind the data tsunami. We need two words: The first is "internet", the place where smartphone users can do pretty much anything, and the second is "app". That's short for "application", a little program that makes a smartphone even smarter. All the big players in the mobile-phone business — Apple, Blackberry, Google, Nokia — now have online "stores" where their customers can download apps for everything from personalized horoscopes to learning how to play zydeco music.

Travel apps make up one of the biggest categories in the smartphone business; and this week we're going to look at a dozen of them, some free, some paid. Let's go!