In a very small way, it always bothers me as a Brit (now living in the US) to see address information ask for (and even require) a ZIP code for int'l customers for two reasons:

1. ZIP is a US-only term. Sure, it's easy to figure out, but it's postal code everywhere else in the world. If an address form has a country field, the form should at least change the label accordingly. If not, even just writing "ZIP/postal code" makes at least some attempt to avoid US-centric terminology.

2. Some countries don't use a postal code system at all. I've seen services make this a required field, regardless of country.