Have you ever seen one of those Flash navigational menus where the hover color fades in and out? You know, the ones where you point to an item and it doesn’t just change color abruptly, but fades into the other color?
CSS-Tricks.com has a great tutorial up, teaching how to do just that. Color Fading Menu with jQuery.
It’s a neat effect, and though it’s not entirely necessary, it can make your navigation a little more interesting without detracting from it usability or SEO-wise.