http://wordpress.org/extend/plugins/platinum-seo-pack/
http://wordpress.org/extend/plugins/google-sitemap-generator/\
This plugin will create a Google sitemaps compliant XML-Sitemap of your WordPress blog. It supports all of the WordPress generated pages as well as custom ones. Everytime you edit or create a post, your sitemap is updated and all major search engines that support the sitemap protocol, like ASK.com, Google, MSN Search and YAHOO, are notified about the update.