Currencies is one of my favorite iPhone apps, and Edovia released a version for OS X this week.
It works the same way as its iOS sibling. Clicking on the currency symbol next to each lets you switch among U.S. and Canadian dollars, yen, pounds and euros. Clicking back on the dollar amount brings up a keypad and you can enter the amount. Double-clicking on each number field will clear it.
The preferences will let you set your preferred keyboard shortcut and a currency refresh rate, though you can also refresh at any time with a keyboard shortcut or through the app.
There are a couple of drawbacks to desktop Currencies. The iPhone app has more than 130 currencies to choose from, but the desktop version has five at the moment. I suspect this will change very quickly. There