The GTranslatifier Jetpack feature helps you translate web pages into other languages.
Info
Installing the GTranslatifier Jetpack feature
If an info bar did not appear at the top of this page asking for confirmation to install the GTranslatifier Jetpack feature, you need install the Mozilla Jetpack Firefox plugin and then visit this page again after restarting your browser. If you trust me not to do anything malicious with your browser, click the check box for auto-updating this feature while you are on the install page.
Uninstalling the GTranslatifier Jetpack feature
Go to about:jetpack, click on the Installed Features link, and then click on the uninstall link next to GTranslatifier.
How to use
To translate a web page, just click on the button to translate the current page into the language selected (which defaults to your native language). Do the same thing for translating a specific portion of a web page, select the text you wish to translate and then click on the button.
Changing translation language
To change the translation language, click on the drop-down selection menu next to the button, and select a language to translate to.
Source code
The source code for the GTranslatifier Jetpack feature can be found at gtranslatifier.js.