Nav Menu Images
This plugin enables you to upload images for nav menu items on a menu edit screen. By default, those images will be displayed instead of text for respective menu items. Note that after upload, you should set an image as 'featured' to be able to display it.
You can also set images that will be displayed only when you hover menu item, or when menu item is of currently displayed page. Read detailed instructions about using plugin.
Developers can use many available filters to make their own way of displaying images, or even create a child class on top of base one. See source code for more ideas.
Although this plugin displays uploaded images out of the box, it will probably not give best possible look, so it's recommended to create custom CSS styles for affected elements.
Nav Menu Images code is partly based on a code from now defunct plugin Custom Menu Images by Anabelle Handdoek /∞manos s.a.s and a code from plugin Metronet Profile Picture by Ronald Huereca/Metronet Norge AS.