Alexa toolbar is a tool that is used by Alexa to measure website statistics. It provides information about the current Alexa ranking of the website that the user is visiting. Alexa traffic rank measures the popularity of the website by measuring how many people visit the website while having the Alexa toolbar installed. While it is not perfect, Alexa is one of very few rankings which can actually quite accurately estimate how popular your site is. Because of this having high Alexa rank will help the ratings of your blog, which in turn will make your blog look more professional in the eyes of your visitors. In my opinion, it is extremely important to have a good Alexa rank if you are serious about blogging in general. If you use Firefox it is a good idea to install the toolbar, as it will boost your websites rank if you visit your website often. On the other hand, it is also a good idea to recommend your readers to install the toolbar, because it will boost your website ranking as well, while providing interesting information and graphs to your readers about the websites that they visit. Sites that encourage their readers to install the Alexa toolbar have usually higher rank because of it. You can download the toolbar at this address: http://alexa.com/site/download. Currently, Alexa only offers toolbars for Internet Explorer and Firefox, so hopefully they will add even more toolbars.