This plug-in limits the classes WordPress added to navigation menus to only those desired by the Theme owner,
adds a unique ID to each li and removes any empty class attributes.
More about this plug-in can be found at:
http://aarontgrogg.com/2011/09/28/wordpress-plug-in-navigation-menu-ids-classes/
Please let me know if you have any questions/suggestions/thoughts,
Atg