We did this theme last year and our ward loved it. We live in a very diverse area, and our ward members are from all around the world or have lived all around the world. So we thought it would be neat to have ward members decorate a table with items they have from around the world. The decorations ranged from small flags and books, to dolls and other toys, to Christmas decorations they collected while living or visiting there, etc.
For dinner that night we had ward members sign up to bring a main dish or a dessert from a certain country. We had enchiladas from Mexico, Lumpia from the Phillipines, Shepherd's Pie from the UK, Red Cabbage from Germany,as well as great desserts - crepes from France, Swiss cookies, etc.
We also had a sing along from the Reader's Digest Christmas song book. We sang 4 or 5 different songs from different countries, like "Bring A Torch Jeanette Isabella" from France, "Christmas in Killarny" from Scotland, "O Tannembaum" from Germany, etc. We had a flute, violin, and piano play along. We had a missionary in our ward at the time from Hungary so he got up and sang a Christmas song in Hungarian.
A sister in our ward from Spain even made a piƱata for the kids at the end of the night!