I used my iPhone for work in the US and when I came here I cried and sold it and used my husbands old clunker (it did the job) but then I finally got the iPhone 4 and everything is right in the world once again.
My can't live without Apps:
GPS! That thing gets me EVERYWHERE!! Its what I depend on the most, especially with all these side streets that lead nowhere
Skype - if you don't have a subscription, then the only "calls" that are free are when you connect to another Skype user when they are logged on. If you want to be able to make calls internationally, my subscription costs me $14 a month and I can call ... 20? 40? different countries. I can call any phone in the US and I can call landlines in the UK. I also have a Skype to go number so family and friends can dial a NY based number that rings me through skype.
Facebook. Nuff Said
WhatsApp? This allows me to text friends and family directly from my phone for no cost (My phone uses the internet to connect. So I can text friends from the states at any time. This works with iPhone, Android, Nokia and Blackberry. I can also send pictures and video. They have to have the application as well.