When it comes to free seo software there is only one place to go.  SEOmoz has the best free seo software tools out there.  Here are a few things their tools do.

Domain Authority - Identify the domain authority of your site and you competitors.  This is a key number, which is a more amped up version of page rank.

Most Powerful Links in - You will see all the links coming into your site ranked by page authority and whether or not they are no-follow links.

Anchor Text - Find out all of the anchor text of all of the links that are coming in to your site.