Currency Assistant is a very complete currency calculator. It comes with a huge database with lots of currencies from around the world. They all seem to be up-to-date, and the application even boasts automatic updates from European Central Bank, the Bank of Canada, the International Monetary Fund and the Bank of Italy.
When you first run the application, a configuration assistant will ask you what are the currencies that you often convert, and it will create a calculator for you. This calculator will only show the currencies that you selected in the previous step, but you can easily add more or change the ones that are there. To start a calculation, you simply type in the amount you want to calculate and it is instantly calculated. You can calculate using any currency that you have added as your start amount, and it will show the calculated amounts in all of the other currencies.
You can also access the entire database of currency values, which has tons of values and it is searchable. This window shows all the values of currencies against the Euro, and not the Dollar. This was a bit hard to get used to at first, but values are values, and they are pretty much all the same.
All in all, this is a great tool which is very well made. It is a very quick way to do calculations and getting results. There is support for tape printing and currency highlighting. The automatic updates are a most in an app like this.