Can someone explain this one to me?

http://www.webmastereyes.com/

Yes, it shows page rank of the url, it also shows PR of all the links on a page too. How can this help with internal links? What adjustments does a webmaster need to make to change the internal page ranks?

It just shows the PR of the pages linked to in your site, internal links included. As for the benefits of this, I don't know.