catfriend creates desktop notifications when new mail arrives. It supports window managers that implement the freedesktop notification specification which includes KDE and GNOME. It can be configured to check multiple email accounts using a simple configuration file.
PHP Easy Ticket System is a full blown help desk application that you can use for support, reports, errors, feedback, or a help desk. It has administration control and users can check how their tickets are coming along.
Login Alert is a small one click wizard GUI that sets up scripts on your Ubuntu/Debian Linux box. It provides SSH brute force prevention through iptables, SSH and local login email alert notifications, and the ability to install fail2ban and denyhost with a click of the mouse.