The HTML5 input types are great, Opera\'s new built-in date picker is a breeze, and Chrome has at least supported the new input type with a spin-wheel implementation.
Javascript
document.getElementById('date-field').value = new Date().toISOString().slice(0, 10);
Jquery
$('#date-field').val(new Date().toISOString().slice(0, 10));
Another Option
If you want to customize the date, month and year just do sum or sub as your wish