I usually just keep some paper notes on my personal trips as I have a good idea of my budget and what will fit into it.

Family, however, has upcoming three weeks in Germany and France with a definite budget. I've looked at a variety of apps in the Apple App Store (wife and I both have iPhones 4/0). I want to use mine to keep a fairly accurate accounting of what we spend, on what, allowing for Euro/US$ conversion, and keeping a running total in each category (lodging, food, transportation, etc.). Would like to be able to total each day and grand total at the end.

Have looked at Tripit and a couple of others more finance oriented, but the number of possible solutions appears to be endless. Does anyone have any suggestions for an app I can use on this trip (possibly on future trips, but not necessary)?