Trail Wallet is an expense tracking application for the iPhone. The app lets you set a daily budget and tracks your spending toward that. This budget then rolls up into a monthly total. There is also a simple system for categorizing your spending. Also in the latest version you can add new categories to better fit your travels. I am not sure I will ever need to use the pre entered category of bribes, but it is there if you need it.
You have the ability to use local currency and input the current exchange rate to you home currency so the app will do the for you. This is of great use traveling internationally. Trail Wallet supports every currency I have ever heard of from the Afghanistan AFN to the Zambian ZMK.
Trail Wallet lets you export your records as a .CVS file and email so recorders are in more locations than on your mobile device. The app also creates simple colorful pie charts to visualize your spending. Of course, the app give you the ability to tell everybody about your travel spending by tweeting the daily results or a breakdown of your spending. There is no Facebook integration that I see in the current version.
After using Trail Wallet on a few trip, I must say I like it. I really see it as more for the independent adventure traveler trying to do things on a tight daily budget, but I have made good use of it on family and business trips.
Disclosure: A free copy of this app was given to a volunteer with the expectation that they would write a fair and honest review of it.