If you have a Mac and not yet installed GROWL, do so now…
You will start receiving messages from almost all the applications that supports growl (and they are many)… Last.fm will display songs being scrobbled, speed download will display started/finished downloads and twitterific will inform you of new tweets..
If you install also the HardwareGrowl from the Extras directory, you will see a message for every hardware device being connected or disconnected from your mac, either USB/FireWire/Network. I tell you, growl application is a MUST !!!!
Also you can send your own messages onscreen with growlnotify terminal executable and even use it from your own software to display whatever you want on screen