
We’ve seen a number of notifiers for various Google services, the latest being Google Notifier Wave, but if we are heavy users of these services, one that integrates them all, as GoogSysTray will be the best option.
This application runs in the system tray and monitors Gmail, Google Voice, Google Calendar, Google Reader and Google Wave, warning you when new one of these services. The notice is customizable for each, showing the notification, playing a sound, running an application, …
Not only that, but above
GoogSysTray we can perform various actions on each notice. For example, upon receiving a new mail can mark it as read, as spam or delete from the notification itself, saving the time of going to the web interface to do so.
The application is compatible with both Windows and Linux, although the latter requires us to have installed Python and pygtk.
Source: Genbeta
More information: GoogSysTray

Why don't you make one?