1. Google Toolbar : This toolbar helps you harness the power of Google Search and various other things like automatic form filler, translation etc. The biggest use of GToolbar is that it displays the PageRank of the websites, so know that which website is popular according to the page rank.
2. Stumble Upon : Easily share popular links and various posts which will drive traffic to your and your friend’s blogs. There are many guides which tell you that how you can easily drive traffic to your blog through StumbleUpon. Now, that you’ve found this post useful, I’m sure you already know that what you have to do with your newly installed toolbar :).
3. Adsense notifier : Keep track of your Adsense earnings easily and see how much you money you make as it updates every 20 min. (by default) and you can keep an eye on some strange activity which will ensure that you don’t get your account blocked if someone clicks on the ads frequently just to help you.
4. Colorzilla : This cool extension can help you pick up your favorite color code from various websites or images with the help of an eyedropper. I’m sure that while redesigning your blog you’ll need this tool for sure.
5. del.icio.us bookmarks : I can’t imagine my life without this extension at all. It helps me in keeping all my bookmarks in a safe place. I do install many extensions regularly and I format my computer regularly, with this extension I know that my bookmarks are stored on the secure server of del.icio.us (a yahoo product) so I know that my bookmarks are not going anywhere even if Firefox crashes or as a matter of fact, my computer crashes.
6. Smart digg button : This smart digg button finds out if the URL has been submitted to digg or not, if it has then it shows you that how many digg that URL received and if not then it lets you digg the URL without any much hassles.
7. Greasemonkey : This is one extension which not just bloggers but every Firefox user must use as it allows you to make some wonderful and useful changes to various web services. It helps you in making applications powerful and thus reduces the time spend in doing certain task and you can either take small breaks or you can easily use that saved time in making extra posts.
8. iWebTool : iWebTool is a collection of around 30 webmaster tools and thus can help you in finding lots of information about a certain website or the best your own blog. This will help you in finding out that where exactly your website stands in various search engines and thus can help you in optimizing your blog accordingly.
9. Shareaholic : This service allows you submit the URLs not just to Digg or StumbleUpon but various social bookmarking sites. This will allow you to make those dedicatedly written post of yours to thousands of users in couple of clicks!
10. ScribeFire : This is one extension which lets you make blog post to various blog services (including blogger, WordPress.com and even self hosted blogs) and I’m sure it becomes pretty easy to make blog directly from your browser as you surf the web and find out something interesting.