There are many sites that will check your SEO score but how many of them actually help? I have found the most useful SEO score system on the web and I have used many in the past.
WebSite Grader: http://website.grader.com/
“Website Grader is a free seo tool that measures the marketing effectiveness of a website. It provides a score that incorporates things like website traffic, SEO, social popularity and other technical factors. It also provides some basic advice on how the website can be improved from a marketing perspective.”