Is there a plugin to allow all the WPMU Sites in my network to share one menu?

I am looking for a way to set up my sites, which all use the same template to share the same navigation. I will be using a megamenu to set everything up, but I don't want to have to change the nav in 8 places every time I add/change something. Is there a plugin, or some line of code I can update?

Thanks!