The article source:http://plugins.jquery.com/project/naviDropDown

Here is a jQuery plugin which allows you to create a simple drop down menu, utilising hoverIntent, and jQuery’s own slideUp and slideDown effects. You can also set the orientation of the drop down depending if your navigation is horizontal (default) or vertical, and set the duration and easing method of both slideUp and slideDown on initiation of the plugin

$(function(){
 
    $('#navigation_horiz').naviDropDown({
        dropDownWidth: '300px'
    });
 
    $('#navigation_vert').naviDropDown({
        dropDownWidth: '300px',
        orientation: 'vertical'
    });
});

Parameters:

dropDownClass: 'dropdown', //the class name for your drop down
dropDownWidth: 'auto',  //the default width of drop down elements
slideDownEasing: 'easeInOutCirc', //easing method for slideDown
slideUpEasing: 'easeInOutCirc', //easing method for slideUp
slideDownDuration: 500, //easing duration for slideDown
slideUpDuration: 500, //easing duration for slideUp
orientation: 'horizontal' //orientation - either 'horizontal' or 'vertical'

Limitations:
Version 1.0: The default width of each dropdown is set to auto, so the automatic width will adjust to the width of the button for which the drop down is applied to. The plugin does not automatically calculate the width of the dropdown based on what is within it. You can manually overide the width from initiation – this applies to horizontal and vertical orientation. This is a basic jquery drop down menu, which obviously could be expanded, but can be customised further using CSS.