Mouse Gestures

One of the reasons why I'm using Firefox as my default browser is because of the add-ins. Mouse Gestures is an add-in for Firefox.

Allows you to execute common commands (like page forward/backward, close tab, new tab) by mouse gestures drawn over the current webpage, without reaching for the toolbar or the keyboard. You can also use click-only "rocker" gestures which are even faster than drawn gestures.

_{Source: JKonTheRun.}