Light weight parallax that uses images not background images and just what I needed. WIll post markup and css later. Needs cleanup too. Expects element to be passed containing the image used as the background. kind of specific for now.

parallax

(function ($) {
  var $window = $(window);
  var windowHeight = $window.height();

  var Parallax = function (element, options) {
    var $this = $(element);
    var $img = $this.find('img:first');
    var obj = this;
    var thisTop, maxOffset, thisHeight;
    
    var settings = $.extend({
      heightOffset: function(){return 0;}, //can be used to offset theheight of the element
      speed: 1 //max movement with image size and viewport
    }, options || {});

    //TODO: pull this out maybe?
    //dont want this in measure because im not updating for window resizing
    //too expensive, not that important
    $this.css({'height':windowHeight-settings.heightOffset()+'px'});

    var measure = function () {
      windowHeight = $window.height();
      thisTop = $this.offset().top;
      maxOffset = $img.height()-$this.height();  //pixels extra to work with from the image
      thisHeight = $this.height();
      //top = $this.offset().top;
    };

    var update = function () {
      var pos = $window.scrollTop();
      
      // Can we see it?
      if (thisTop + thisHeight < pos || thisTop > pos + windowHeight) {
        return;
      }
      
      // How much can we see?
      // how much have we shown divided by the element + window height
      // tells us what percent we have scrolled through the item. 100% is off screen, scrolled past
      var ratio = (pos+windowHeight-thisTop) / (thisHeight+windowHeight);

      //take the max numbers of pixels we have to work with and figure out how much to pull off screen
      var offset = -(Math.round(ratio*maxOffset));

      $img.css('top', offset + "px");
    };
    
    //TODO: section seems poopy...
    $window.on('scroll', function(){      //just update
      update();
    }).on('resize',function(){            //recalculate
      measure();
      update();
    });
    measure();
    update();
  };

  $.fn.parallax = function (options) {
    return this.each(function () {
      var element = $(this);

      // Return early if this element already has a plugin instance
      if (element.data('parallax')) {return;}

      // pass options to plugin constructor
      var parallax = new Parallax(this, options);

      // Store plugin object in this element's data
      element.data('parallax', parallax);
    });
  };
})(jQuery);