In this post i'd list of top 8 enhanced drop down menu modules for Joomla 1.6 & 1.7 which allows you to show subitems segregated in mulitple columns. Those module very easy to use, just install the module and select a menu from Joomla menu system then publish it to a position which you want and see that effect.
Then you will need our Dropdown Mega Menu! Just by installing it, replacing it to your existing horizontal menu, you now have a Dropdown Mega Menu on your website! Very quickly and conveniently.
ARI Ext Menu v. 2.0.13 is ready. It provides minor improvements. Supports horizontal and vertical menu direction
a new menu module. But the powerful IceMegaMenu extension is not the next simple menu module that you may find anywhere. No I'm sorry you will not...
Dj-MultiTreeMenu is an enhanced drop down menu, which allows you to show subitems segregated in mulitple columns.
The menu used on Joomla.org sites. You can see it in action on the top of this page.
The Dropdown Mootools Menu is a joomla 1.5, joomla 1.6 and joomla 1.7 native smooth menu module, it allows you to display your joomla menu in a horizontal drop down style.
RokNavMenu is a powerful menu module which provides functions above and beyond the capabilities of the core Joomla menu. It provides a feature rich platform for extending the menu, allowing for overrides and plugins for the menu itself, in addition to versatile theming capabilities and so much more.