If you send a wedding invitation to the President, you will receive a congratulatory letter from him and the First Lady. I don't care who the president will be when I get married, I have to remember to do this! PS: it works for Mickey Mouse, too!
"An easy way to track RSVPs! Guests often forget to write their name on the response card. With this invisible ink pen, just number your guest list and write that corresponding number on your RSVP card. They'll never know it's there!" So sneaky!