Previously I discussed about the Pidgin-libnotify plugin which automatically "notifies" your when new messages arrive by using a dedicated icon written for the Unity's launcher, just like that, would you like to see a live preview (as in the above screenshot) of the files that you downloading via the Firefox4 web browser directly in your app launcher in Ubuntu 11.04 (even when the web browser is closed or minimized!).
If so, then you should install the plugin called UnityFox. This is actually a Firefox add-on! which again shows the power of the (not sure if Unity comes with a fully compatible GNU license, there are few issues) open-source application standards and how easy it is to integrate new features into them.
Anyhow, if you want to use this, then make sure you you're using Ubuntu 11.04 and download the add-on from here.