Honestly, I only use google toolbar for autofill, auto translate and PR check but other than that I use other add ons to maximize my job as an SEO. Maybe my third party add on for auto form filler is my top favorite in my toolbar list.
I only installed Google Toolbar on my browser though I don't actually find it as my favorite one because I seldom use its features.
Currently im using firefox 5 with firebug , screengrab and alexa installed. Since the official google toolbar no longer works on Firefox 5 I have totally removed it .
My Favorite Toolbar is * Google toolbar * Rank Checker Bar * Nodofollow Chaker * Facebook Side Chat Bar
After Google toolbar, my favorite is Speedbit video download toolbar. This makes me enable to download any video that I can play.
My favorite toolbar is SEO book and web developer toolbars. These toolbars is very useful for SEO purpose.
i also think that google toolbar is the best toolbar, it has many features. With support for live feeds and custom site search, Google Toolbar custom buttons are more than just bookmarks. Now custom buttons can even support Google Gadgets - when you click on the icon, the gadget will pop down from the Toolbar, no matter what site you are on and close when you are done with it. You can add some of your favorite Google Gadgets to your Toolbar.
I really like google toolbar. I always use google toolbar & search status tool in my browser for doing seo works.