As you can tell from its name, this is an un official extension that allows Firefox to take advantage of Google’s well known "Gbar".
The Google toolbar was not available for Firefox as of the 8th of July 2005 (see news), so Internet Explorer was the only browser that could take advantage of this for 4 years!
This is the reason that there is a non official extension available.
For those of you that don’t know what it is, the Gbar is a small tool bar that is dedicated to Google search functions. There is a search field so that you can directly search anything without going to their web page, as well as a number of buttons and shortcuts that can be customizable to your needs or habits.
The default options will be satisfactory for most people, bit if you still want you can personalize your Gbar. As you can see from the screen capture below, you can also add or remove shortcut buttons. You can also change the language if you feel like it.
As there is nothing really interesting to demonstrate here I’m going to let you have a look at the options yourself.
To access these options there is nothing simpler; all you need to do is click on the "G" to the left of the Gbar and under the Firefox toolbar. You can see this below in the screen shot.
Download Google Bar extension