There are already plenty of ways to send notifications out of Firefox into apps like Snarl and Growl, but what about the other way around? If you work, play, and live in your browser wouldn't it be nice if your notifications could appear there instead of needing to install a standalone notifier?

The Notify addon for Jetpack does just that. With a short snippet of JQuery code, developers can easily push notifications to Firefox. They'll appear even when sent from background tabs or from external applications, as long as Firefox is still running.

Zach Waugh, who created the addon, has made all his code available under the MIT license, so you're free to use it in both commercial and personal apps.