During a recent visit to the Czech Republic, I put my iPhone 3GS to good use as a general tool for blogging, notetaking, translation and navigation. Some of these uses are obvious; the compass is invaluable for getting your bearings when lost in Prague's maze of tiny streets, and the Maps application is very useful as long as you have connectivity.
Unfortunately, there is no Orange service in the Czech Republic so I had to rely on the numerous wifi hotspots located around Prague city centre. Fortunately most of these are genuinely free, and do not require the user to log in to a service. Just connect and go.
For translation, I used iSpeak Czech. The translation engine is Google Translate, so real-time translation without a network connection is impossible. There is facility to perform translations and save them, though, and the speech synthesis requires no network connection. In fact, it's possible to just type phrases into the relevent text box and press the speech button to hear an excellent synthesised voice that takes account of proper pronunciation rules. Every time I used it, the pronunciation used by the program was identical to that spoken by locals.
Of course, typing the words to translate was something of an issue. This is where the iPhone international keyboard comes in. When more than one language is enabled, a globe button appears by the space key to quickly switch between languages. Switching the keyboard language also switches the autosuggest and this works as well as expected.
Another nice feature of the iPhone keyboard is that it adds all the accents and special characters to the other keyboards too. This is very handy when typing, for example, a single Czech word into an otherwise English blog post.
For blogging purposes I use Blogpress, for reasons detailed in older posts about iPhone blog clients. It has the easiest image addition UI of all the apps, and will upload photos and even video to a Picasa or Youtube account of your choice. The offline drafts mode means that writing on the go and uploading once a hotspot is found is very easy. There are a couple of niggly bugs but nothing I can't live with.
Finally, for currency calculation I use the offical xe.com app. This has online exchange rate updates, but will use a cached value when no network is available. Quick and easy, as it should be.
So for a pocket-sized travel companion, the iPhone is ideal. Install the apps you need before you travel, and even without a network you should be able to make good use of it. Just don't forget the charger!