1000s music in your pocket! (Touch: OK)

Though it's a kind of obvious factor, music is absolutely essential for travelling. What's more, the integrated speaker makes reasonably loud sound and it's possible to play BGM in dorm rooms.

Making phone calls in case of emergency (Touch: NG)

As the loaming plan will be applied, we must be careful for the amount of usages but having a phone which can connect everywhere gives me a sense of security. Besides the international SMS is not too expensive and can be easily used for contacting with local people.

GPS & Electric compass support your sense of navigation (Touch: NG)

With the electric compass, you can get through in case of losing the way in an unfamiliar town. Though native google map app doesn't support caching the data, with the other apps mentioned later, the GPS becomes killer function of all.

Ubiquitous photo shooting with the integrated camera (Touch: NG)

Though the quality of images is inferior to the normal compact cameras, it is way handy than any other cameras. Personally, I make use of this as a sub camera of DSLR. I like this as I don't need to motivate myself "Well I shoot photos!" Besides, with the apps I can add colour modification on site without using PC.

Internet connection with wi-fi (Touch: OK)

I guess Safari is sufficient enough for the casual browsing during the trip. What's more some sites like Facebook, twitter and google reader have dedicated applications which in fact give far better user experiences than normal browser. Many hostels provide wi-fi and if you always have iPhone in your pocket it's possible to connect with free wi-fi spot unexpectedly found at restaurants and shopping centres.

For a photo viewer (Touch: OK)

The photos taken by other cameras can be saved in iPhone after organizing. Although the resolution is not really big as the other high-end smart phones, the colour is as good as the apple products. The display ratio is 3:2 which is suitable for the photos from DSLR. Besides as iPhone is basically a “phone”, you can casually show off the photos to the other people.

Applications for travelling

I realised that it might be possible to archive all the functionality above with the other smart phones. Nevertheless, the foremost enticement of iPhone is its vast variety of applications. This time, I'd like to introduce 6 applications which is specialised for travelling.

OffMaps
A map application which caches information locally. In other words, after downloading the data at accommodations, we can check the map info on streets without the net connection. As this app uses open source map information, it's not as precise as google map but adequate for strolling around the roads and of course works well with integrated GPS function.

iTravel
A dedicated browser for wikitravel and this can actually caches information locally after browsing. Incidentally, there are two versions of this app, free and paid. According to the author, there are no differences between two and uses can buy the app as a sort of donation for him.

Lonely Planet Travel Guides
The iphone version of the famous guidebook series. Plenty of guidebooks and phrasebooks are available with the internal purchase. The guidebooks have their own map and sort information according to the location using GPS. Thanks to this and iTravel, I don't need to carry any physical guidebooks. Though the price of each book is slightly expensive as a iPhone app, it's worth buying if you stay a city bit long and need detailed information.

eCurrency
A currency convertor. Though there are some free apps in this category, I like this for its UI.

Lingopal
A phrasebook which can translate amazingly more than 40 languages. Though there are separated versions, round the world travellers must have all include version which costs merely 10USD. Honestly the quality is actually so-so(too many flirting phrases!) but anyway it's very interesting to have phrases in many languages. Not only for general greetings, it's useful for making topics during the conversations.

GoodReader
I must mention this although this app is not specialised for travelling. This is a quick document file viewer. Usually, e-tickets are often sent as PDF and it takes time to print them out. But actually I save them in GoodReader and show iPhone at the counters. Nobody at the airport refused this so far.

Besides these, there are so many useful apps like Skype, Kindle for iPhone, Read it Later etc, in the App store and some games are absolutely perfect for killing time.

Conclusion

In fact each function can be substituted with the other devices. Yet the best thing of iPhone is that you can have all of these with the palm size gadget. This is why iPhone is indispensable for the all travellers who want to reduce the amount of the luggage.