Mozilla Jetpack: Explore new way to personalize your web

Jetpack is a newly formed experiment in using open Web technologies to enhance the browser, with the goal of allowing anyone who can build a Web site to participate in making the Web a better place to work, communicate and play.

In short, Jetpack is an API for allowing you to write Firefox add-ons using the web technologies you already know.

As with all Labs experiments, Jetpack is an open source project and everyone is welcome to participate in its design, development and testing.

Jetpack is web-based.

• HTML, Javascript, and CSS will be the only tools required.
• Have the full power of the open Web: AJAX & multimedia capabilities.
• Streamed & accessible via a URL, just like the rest of the Web.
• Debugged in the browser.
  

Check the Mozilla jetpack Site for more and create your own addon. You can also check out the some of the demos of jetpack applications like UnAds, Email Notifier etc.
The below video demonstrates how to install Jetpack and use it.