Webmaster Tools - PageRank Checker
Want to know what the PageRank of websites are as you surf? If you are using Firefox, take a look at the Search Status addon. It gives you quick access to Google’s PageRank, Alexa rank, and a great list of other features. The features I use most often are the “Show Indexed Pages” and “Show Backward Links” to quickly check how many pages from my site have been indexed by the search engines, and how many links there are at the site. The Search Status addon has my vote as an esential Firefox addon for webmasters.
If you don’t want to constantly be checking your PageRank give iWebTool’s PageRank Checker a look. It will check your websites PageRank on all of Google datacenters. A very quick and easy tool to use if you just need to check a site occasionally.
Search Status Addon