The couple in question may or may not have their honeymoon all planned out already, but you don't have to know where they're going to plan a worldly bridal shower in your girlfriend's honor. Sometimes, all you need to spice up an event is a bit of flavor from around the world.
The geographical scope of your event is entirely up to you. Stick to one location if you'd rather have a consistent, easy-to-pin-down scheme (if you're stuck on ideas, ask the bride-to-be where her favorite part of the world is).
Otherwise, you can be totally open-ended and mix global influences from every corner of the world for a lively, multiculti bash. This is perfect if the nearlyweds are seasoned travelers and love collecting objects from the strange lands they visit. Challenge guests to bring unique houseware items from exotic locales. A bamboo coffee maker from South Africa or a set of Indonesian wind chimes would make ideal and memorable gifts.
In exchange, kick up the cultural flavor by offering guests little souvenirs they may well have gotten on their trips abroad - colored paper hand fans are an easy reminder of Japan, while some of the francophiles on your guest list may appreciate a fleur-de-lis scented soap favor.