Google Toolbar can be downloadaded here for free. The google toolbar is a must have tool for webmaster and seo guys.
Although there are many toolbar out there that provide pagerank information on it, the google toolbar is the only choice for displaying the exact pagerank information. It also has a less consuming time on searching on google, show how many url linked to particular website, and don't forget a popup blocking tool to prevent your browser to display otomatic triggering pop up page.