Magento layered navigation filtering URL's with name not id

Actually as far as I know Magento doesn't support the SEO friendly URL's. you might wanna try this extension. We use in on several shops and adds some nice extra features to the layared navigation besides pretty urls http://amasty.com/improved-navigation.html

This is supported by GoMage's Advanced Navigation plugin, which, among other things gives you Ajax categories, multi select layered filters, infinite scroll. One of my favorite plugins. They don't charge extra for EE, either.

http://www.gomage.com/extensions/gomage-advanced-navigation.html