Nice Search is a WP plugin that makes your blog search “SEO friendly”.
It’s in quotes because normally search results won’t get indexed by search engines, because they are dynamic. Unless of course you store them as a static page in a specific folder in your blog.
But the plugin is still very useful, it makes your search strings “nicer” as the name of the plugin says. As you can see from the screenshot, it turns the normal wordpress search string into /search/keyword format, which is a lot more readable.
Plugin page: http://txfx.net/code/wordpress/nice-search/