A often-used practice in Responsive Web Design is to replace the menu/navigation (<ul>) with a dropdown (<select>) on small devices, this to prevent it from taking up the whole screen.
Today, my friend Jochen released a jQuery plugin that does the job for you automagically:
jQuery Mobile Select is a jQuery Plugin to replace the site navigation with a dropdown for mobile devices
Here’s before and after:
Bloggink: Mobile Navigation jQuery Plugin →
jQuery Mobile Select Source →