This site uses a few different extensions for Search Enginre Optimisation.  The main ones are:

• OpenSef 2.0.0-RC4 (http://www.open-sef.org/ ).  This extends the default Joomla SEO functions for human readable links, so links are really human readable.  It works, and it's great.
• For google sitemaps I use Google Sitemap generator V2.0.5  (http://forge.joomla.org/sf/ projects/google_sitemap_generator )
• To Make The google Sitemap plugin use the OpenSEF URL's I use a plugin for OpenSEF (http://www.open-sef.org/downloads/ other_addons_developed_by_the_opensef_team.html )