If you are talking about PR, just download the Google Toolbar and you will have the pagerank of your site.
SEO consists of a lot of factors. You can try out my SEO Tag Analysis tool for some general guidelines
seo score is a fictional score someone made up......probably as a linkbait idea...and I guess it worked.....there is no official SEO score...
I assume you are talking about the score you get when you use whois.domaintools.com ? I do not know what criteria they use, but it does look like you are referring to that one. In actual life, the better you rank for your keyword, the better your score is
i think seo score is your traffic which you are getting from google because of this , the best seo score tool is google analitics