Perhaps not what you're looking for, but... Learn a language of a country that you might be doing business with in the future. Sure, everyone speaks English (d

Perhaps not what you're looking for, but... Learn a language of a country that you might be doing business with in the future. Sure, everyone speaks English (do they though?) but even a little bit of their native language goes a long way establishing goodwill. Even if not for profit, it grows your mind and that is never a bad thing.