I modified my phpstates code include to display countries and Canadian provinces as well. The country codes come from the UPS developer’s API. This is another one of those snippets that I use often, so maybe it will help you out.
I was looking for a quick and simple PHP function that would validating credit card numbers, but the code I found was mostly clunky and sometimes just wrong. I wrote this function and it seems to work correctly. Feel free to use it and leave a comment here if it works for you.