For those who aren't in the know, let me explain.
Growl is a multi-app notification tool. Currently, I have it connected to my itunes, my facebook account, amsn (or adium) and transmission (my torrent client).
Everytime an action occurs in any of these applications (for example, someone sends me a message on amsn, someone comments on my wall on facebook, a torrent finishes downloading or there is a song change on itunes) a small window pops up in the corner of your screen notifying you of the action. The only downside, is that you when you click on the notification, it doesn't take you to the application, it simply makes the notification dissapear faster. You can of course add sounds for each different notification, but I choose to avoid that.
Anyways, here's the link!
I would recommend going to the applications section of the growl site to download the needed plugins to connect growl to itunes etc.
and here is the link for the facebook plugin called FMenu