If I could have one app on my phone when I am on holiday, this would be it. The ability to head into a general area and then use the GPS features to find other nearby attractions, restaurants, etc and then point me there with a simple arrow is seriously amazing - especially without needing to get a SIM card for data.
This app has literally changed the way I travel - I now spend a lot more time doing and enjoying instead of planning or missing out.
Not only do I use XE Currency nonstop when I travel, I also use it all the time at home when checking forex rates or making overseas purchases. It is incredibly convenient after you configure the few currencies you're interested in, and has prevented all those costly miscalculations I used to make when manually converting foreign currencies.
While I am already quite meticulous about managing my trips in Excel spreadsheets, calendars, and DropBox folders, WorldMate is a must-have tool to always know when/where my next flight is and what hotel we to go to. The simplicity of opening the app and seeing everything neatly organized at your fingertips - all without doing anything other than forwarding confirmation emails - is magical.
Use the offline map functionality to cache maps that you can later use when you're out and about without internet access. The maps are saved on your phone and the location is based off of GPS, which is always free and requires no SIM card / telco connection.
