Hey there, IMHO, Google Analytics, Siteexplorer and GWT are best. Among the third party tracking tools SEOcentro, Spyfu, Woorank (but not recommended as a completely reliable tool), website grader are a couple of ones. Depending on your tracking requirement you need to filter the prevailing free SEO analysis tools. Thanks Krish India Design
SEO on google, use: google webmaster, siteexplorer.search.yahoo.com competitor analysis, use rank tracker, spy full ......
There are lots of free seo tool which may help you to know the seo values of that particular site. Some tool may help you to know its backlinks, traffic etc.