var ws = [
'http://www.amazon.com/gp/registry/registry.html?ie=UTF8&type=wishlist&id=RCR3TQMIRWKI',
'http://www.amazon.com/gp/registry/registry.html?ie=UTF8&type=wishlist&id=3UUY7SMDNXIN9'];
var i = parseInt(new Date().getTime()/(1000*60*60*24)) % 2;
var url = ws[i];
document.getElementById('want2saythanku').setAttribute('href', url);