Check out the online currency converter for MacOS X. It was developed on Snow Leopard and targeted to Snow Leopard users.
You can choose to work online or offline. When online, the program fetches the conversion rate from the internet and used for your conversions.
Feedbacks and suggestions are welcome! Also, you like the software and want to show your appreciation, please, donate using the link below!
Download for MacOSX 10.6:
Here are some screenshots: