I recently added a summer vacation countdown clock to the website of my kids' school:

var backToSchool = new Date(“August 26, 2002”);
var today= new Date();
var msecleft = (backToSchool.valueOf()) – (today.valueOf());
timeleft = Math.floor(msecleft/(1000*60*60*24));
document.write(“

Days left until school starts:

” + timeleft + “

“);

I think I'll show it to my kids every now and then.