KCheckGMail is a simple KDE systray application that notifies when new email is received in a Gmail/Google Mail/Google Hosted Domains account.
I was not very impressed with this application. There are very important features missing like support for a mail client like Thunderbird, Kmail, Evolution... There is now way to mark new mails as unread, after reading the new mails. this functions is also missing, there could have been an option included in the right click menu bar to do this.