If you use Gmail for your email account and you are a Mac user, then the Google Notifier may be a useful tool for you.
The Google Notifier is a tool available for Mac only. It will add an icon to the menu bar on your Mac (the bar on the top of the screen). If you get a new email, a small window will appear on the menu bar and it will show you a preview of the received email. You can then click on the preview window to open the complete email.
Additionally, if you also use Google Calendar, the Google Notifier will remind you of upcoming events on your calendar.
It's a good idea to set up the Google Notifier to start every time you turn on your computer. By doing this, you will be alerted of any new emails or events as long as you are using your computer and connected to the Internet.
If you are interested in this useful tool, please visit the Google Notifier for Mac download page.