This tools allows you check the pagerank of any page you want for free. More than that, you can add a button that displays the google pagerank on you page. All you have to do is to select and copy the code from the PR image you like and put it in your page source.
This tools checks your pagerank everytime someone opens your page, in this way the pagerank that we display on your webpage is allways up to date.
* The name "PageRank" is a trademark of Google. Google has exclusive license rights on Pagerank algorithm