bound postcards...on your travels, send yourself a postcard every day from where ever you are...then bind them when you return to have a journal of your trip complete with photos, stamps, and a run down of each day's events!!
If you send a wedding invitation to the President of the United States you will receive a congratulations card signed by the President and the First Lady. If you live in the UK you can the same with the Queen. You can also send one to Minnie & Mickey in CA or Cinderella & Prince Charming in FL. This would be cool to get because I have kids