Meebo is an online Instant Messenger application that allows you to run the application from within your browser. This is perfect for those times when you are traveling and need to use an Internet Cafe, or a locked down PC at work that does not allow you to install applications. I wrote about Meebo previoiusly.
To further integrate Meebo into your browser, Meebo has just released a Firefox extension. This adds a pane to the right side of your browser and lists all of your buddies online. You can also ‘disconnect’ the pane and have it work as if it were a stand alone application.