I don't surprise the kids but we have been countiing this trip down for months!! Now that we are closer, I will be starting my lunch bag countdown - I send Disney trivia questions each day in their lunch bag along with a Disney treat (chocolate or candy). They bring me home their answers at dinner (I get these questions from our Disney Scene it game). My DD's are 9 and 12 so this is what we do now but in the past we have had Disney chains that we made - a link for each day to countdown - and we remove a link a day until we go.
I have also arranged a call from Mickey Mouse - I forget the website but google it and you will find it!