For you Firefox users, I have found a really great plugin. SEO Quake Plugin for Firefox
This little plugin adds a toolbar to your browser that gives information on PR – page rank, Alexa ratings, age of page, Whois information, links, keyword density and more.
See the toolbar (or at least a portion of it since it is too wide)
One of the best things about this plugin is that the information is there “at a glance”. Since I got my new computer, I have been using IE again. I may now go back to Firefox with this new addition.
Check it out for yourself!