Define/include "globally available" arrays and functions

Hello,

I'd like to define some arrays and functions that I can access "globally" in all controllers/models/views.
For example I need to define an array of available currencies:

PHP Code:

$currencies = array("EUR","USD"); 


And some functions e.g. to display numbers differently depending on the users country as some use decimal points or commas.

Where would I put those arrays and functions and how would I include them so they are available from everywhere?

Thank you very much for your help
Tom