A friend of mine was telling me how SEO is negatively impacted when the nav menu is image-based or rollover instead of HTML. I'm not sure about this, because there are several sites I've stumbled upon through Google that showed up in the top ranks with image-based nav. Any opinions from resident SEO experts?
The problem with image based menus is that you don't put any anchor text even if you're using a href tag to display the image. So you lose one of the most important factors in that Google relies on to determine what the target page is about.
Generally, these sites will also have a footer menu that is the same as the image navigation using only contexual links; you also need to make sure to properly optimize your images in your navigation, see below link. You should also make sure to always provide contexual side wide links. www.mattcutts.com/blog/matt-video-alt-attributes-for-images/