This was written by Chris Coyier of CSS-Tricks (http://css-tricks.com/snippets/jquery/smooth-scrolling/) I have it here for quick access. I also added an offset from the scroll element, sped up the animation, and have it set to only target links in a tag with the class .nav

scroll.js

$(function() {
  $('.nav a[href*=#]:not([href=#])').click(function() {
    if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'') && location.hostname == this.hostname) {
      var target = $(this.hash);
      target = target.length ? target : $('[name=' + this.hash.slice(1) +']');
      if (target.length) {
        $('html,body').animate({
          scrollTop: target.offset().top - 150
        }, 400);
        return false;
      }
    }
  });
});