This should do the same trick without plugin

$(window).scroll(function () { 
   if ($(window).scrollTop() >= $(document).height() - $(window).height() - 100) {
      //Add something at the end of the page
   }
});

EDIT Jan 15, 2014

According to @pere's comment, it's better to use the code below to avoid excessive amount of event firing.

Inspired from this answer https://stackoverflow.com/a/13298018/153723

var scrollListener = function () {
    $(window).one("scroll", function () { //unbinds itself every time it fires
        if ($(window).scrollTop() >= $(document).height() - $(window).height() - 100) {
            //Add something at the end of the page
        }
        setTimeout(scrollListener, 200); //rebinds itself after 200ms
    });
};
$(document).ready(function () {
    scrollListener();
});

Combining Ergec's answer and Pere's comment:

function watchScrollPosition(callback, distance, interval) {
    var $window = $(window),
        $document = $(document);

    var checkScrollPosition = function() {
        var top = $document.height() - $window.height() - distance;

        if ($window.scrollTop() >= top) {
            callback();
        }
    };

    setInterval(checkScrollPosition, interval);
}

distance is the number of pixels from the bottom of the screen when the callback will fire.

interval is how often the check will run (in milliseconds; 250-1000 is reasonable).

For example the infinite scroll plugin