Strange: openmenu.com doesn't work for me in Chrome. It does work, however, if I prepend it with www. Firefox seems to add the www automatically.
But it doesn't look pretty (in Chrome or Firefox). Something's wrong with the stylesheet and some images. I'm guessing it's because the link to the stylesheet doesn't contain the www.Open Menu Wordpress Plugin
EDIT: IE doesn't like it without the www either, but at least it loads the stylesheet properly!