wp_nav_menu with images

You can achieve this within the same HTML structure wp_nav_menu() produces.

CSS can hide the text using text-indent http://www.w3schools.com/cssref/pr_text_text-indent.asp.

CSS can then be used to assign background images to the relevant menu items.

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Opposing the solution above, you could use cufon or @font-face to replicate the font in the images, providing you have the font file(s).

To replicate the background colours of the images, you could use the unique CSS selectors of each menu item (<li>) relevant. An opacity could then be applied http://css-tricks.com/css-transparency-settings-for-all-broswers/.