IPhones and iPods are becoming essential for travelers--for example, TripIt automatically organizes all of your important travel documents (Photo - flickr user Irrezolut)

The iPhone and iPod touch are quickly becoming essential travel tools.
With the incredible growth of downloadable third-party software (apps) on iTunes, the iPhone and iPod touch have suddenly become an electronic Swiss-army knife for road warriors and avid travelers.
As few as five or six years ago (back when iPods were impressive merely for their ability to play and store large amounts of music), an MP3 player would not be a solution to your travel problems.
Today, the reverse is true: an iPod touch is capable of performing so many functions, it is hard to choose what is worth using–there are simply too many apps to choose from.
What apps are worth getting? Between apps for budgeting, scheduling, translating, and navigating–not to mention apps which serve as guide-books, audiotours, phrasebooks, currency exchanges (in addition to multiple brands serving each purpose)–the hassle of finding the right app can seemingly outweigh any possible benefit they might provide. Instead of wading through all the options, here is a rundown of what’s out there.
One note: many apps rely on the iPhone’s GPS to determine your location and show nearby points of interest. For iPod touch users, this is something to be aware of. While you can still use the app by manually entering your location, this requires wi-fi, and wi-fi coverage is hard to predict in unfamiliar areas.
And there’s the catch: nearly all of these apps work great for the iPhone, and wonderful for the iPod touch–so long as you have an internet connection–but without that, you’re out of luck. This might not be an issue for iPhone users–just a drain on batteries–but for iPod touch users, it’s a game changer.