*. Mark as read.
*. Report Spam.
Another thing is that, unlike with many of these so called notifiers, CheckGmail does not bother you much while "notifying". When you click on "Open" or any other button/link on the GUI, it opens your default browser and takes you directly to the proper location on your Gmail account as well.
So, if you want to try it out in Ubuntu, open your Terminal and issue the below command.
sudo apt-get install checkgmail