There has just been a release of a new extension on addons.mirror.org called SEO Toolbar. Now I think the extension is a great addition to every web masters tool kit. Part of the reason I agreed to update and add many new features to it for the extension's owner SEO Company
The extension displays things like a pages PR and Yahoo! Inbound Link Count that are regarded as important when it comes to getting your pages in the top of the search results. The extension does not just display these two results, it provides an amazing 20 different figures that every web master should check from time to time. This includes the ILQ (Inbound Link Quality) that is unique to this extension.
The extension also provides a handy white-list feature for controlling what sites the results are displayed on.
So go check out its Home page and become a happy user of this extension like so many others are.