Small Business Hub has clean interface to grade your website .Their analysis is pretty neat.
The WebSite grader attempts to measure both the ability for a website to attract traffic and the ability to convert that traffic into qualified leads and prospects. Their algorithm uses a unique blend of over a dozen different variables including search engine data, website structure, approximate traffic, site performance and others.
The report tells you about
Google Page Rank
Your Web Page/Site structure
Web Page Content (Links to Others)
Google indexed pages
Conversion methods (RSS Feed,Sign up Forms)
I tried Grading Google which got 97/100 and yahoo which got 95/100 :)