$.fn.jCheckbox = function(params) {
    params = $.extend(params);
    return this.each(
        function() {
            var $this = $(this);
                               
            $this.addClass((params.checked ? params.on : params.off));
            
            $this.bind('click', function() {
                if($this.attr('class') == params.on) {
                    $this.attr('class', params.off);
                } else {
                    $this.attr('class', params.on);
                }   
            });
	});
};