Setting up a Site with 3 Levels of Navigation

What is the simplest way to set up a site with three levels of navigation? Right now I have two levels, and I have a category group mainpages that contains the first level (about, research, news, etc.) and each level below belongs to one of these categories, and I use channel categories tag to build the navigation and subnavigation. Is there a better way? The three levels of navigation are in different locations, it’s not simply nested dropdowns.