This simple plugin sends desktop notifications when friend appear/disappear, when your nickname is mentioned in the chat and when you're receiving private messages.
Note: Notifications are sent using the tray icon so make sure you have it enabled in the TeamSpeak 3 Client settings.
To make sure the plugin is running and operational, simply enter the following command in your TeamSpeak 3 Client chat area:
/notify Hello World!
The full source code for this plugin is available on Github for your perusal.