This add-on is compatible with Concrete 5.5.
See this add-on in action at: http://c5extras.com/add-ons/mega-menu/

It's finally here! You can now add a beautiful Mega Menu to your website in just a few clicks. It overcomes the difficulty of multi-level drop-down menus by combining multiple submenus into a single drop-down. This is the ideal way of displaying the navigation menu on larger websites. Usability expert, Jakob Nielsen, recommends the use of Mega Menus:
Given that regular drop-down menus are rife with usability problems, it takes a lot for me to recommend a new form of drop-down. But, as our testing videos show, mega drop-downs overcome the downsides of regular drop-downs. Thus, I can recommend one while warning against the other.
- Jakob Nielsen (March 2009)
This Mega Menu is based on the core Concrete5 "Autonav" block so it uses your existing website structure, but with a number of additional features.
The Mega Menu is perfect for everyone: website managers, web designers and web developers. You can choose from 8 colourful skins, or advanced users can create their own skin. The number of submenu row items is customisable along with the animation effect and animation speed.
It's easy to use, but powerful & flexible. The best of both worlds!
Features:
Do you want a VERTICAL Mega Menu? Your wish has come true!
Check out the "Version history" page for a list of the latest updates to this add-on.
Extra videos:
For website managers: how to use the Mega Menu across your entire website (7:26)
For designers: unlimited customisation with Mega Menu (9:22)
For developers: add your own custom menu items such as images & video (7:25)
Check out more of our quality Concrete5 add-ons at our website and follow us on Twitter for exclusive discounts.
*** SPECIAL UPGRADING TIP ***
If you are upgrading to v1.1.4 and have used a custom skin (or edited one of the existing skins), you'll need to re-do your customisations as the names of one of the CSS classes has changed (instead of .mega-menu it is now .mega-menuh) so we can support both the vertical and horizontal Mega Menu add-ons on the same page.