Webconfs is our #1 research tool on the internet right now.  We have found this site to provide insight to websites we have being doing SEO work for.  It has a ton of tools that you can use to check out the health of your site.

 Similar Page Checker 
Search Engines are known to penalize websites that contain Duplicate / Similar content. Your content could be similar to other websites on the Internet, or pages from within your own website could be similar to each other. This tool allows you to determine the percentage of similarity between two pages

Search Engine Spider Simulator (One of my favorites)
This tool Simulates a Search Engine by displaying the contents of a webpage exactly how a Search Engine would see it. It also displays the hyperlinks that will be followed (crawled) by a Search Engine when it visits the specified webpage.

Backlink Anchor Text Analysis
It is not enough just to have a lot of backlinks, it is the Quality of backlinks along with the Quantity that help you rank better in Search Engines. This tools help you determine the backlinks of your website and the link text used by your backlinks to Link to your wesbite.