Firefox Add-on: All-in-One Gestures

Use your mouse to execute common commands by "drawing" on the webpage you're viewing with your right mouse button. It's an awesome extension that can help with productivity. You can go back a page, forward a page, close a tab, etc. I whole-heartedly recommend this add-on and use it myself.

To download from homepage, click here.
Download the Add-on from Firefox's Add-on page here.