$.ajaxProgress = function () {
    var image = '';
}
$.ajaxProgress.setImage = function (src) {
    this.image = src;
}
$.ajaxProgress.getImage = function () {
    return this.image;
}
$.fn.ajaxProgress = function () {
    this.empty();
    $('<span><img src="' + $.ajaxProgress.getImage() + '" alt="loading..." /></span>').appendTo(this);
    return this;
}