I do like this!

Its minimal and nice...

Here is a suggestion though:
Because I only want to use this as a ticker, I only require the readout that appears in the Menubar... It would be cool if i didnt have to have the 'app' open and sitting in my dock while I am only using the menubar part. I hope that makes sense. (an example could be dropbox using it if you have that installed?).

Another suggestion could be:
When you click the menubar item you get a dropdown displaying multiple currencies/24hr average/last price/high price/low price etc.

Great work anyway keep it up!.