OK, I'm being a little facetious. But what you need to remember is that the language, culture and business practice issues don't evaporate just because anyone in the world with a web connection can view your site. Pay attention to them. If you're going to do lots of global business, your site should use the languages of your customers. That's just courteous.
Different cultures prefer different web color choices.
Check out an array of South American or African sites, for example, being careful to choose those not developed by US firms. You'll see that the color choices are often far different from what you see in North American or European sites. Business practice issues vary, too. Many South American credit cards, for example, are not valid for North American purchases or, sometimes for purchases outside the country of issue. Remember that there are three set of factors that go into a good web design.