A simple PHP script which will monitor your mailboxes and display nearly real-time information about your users' POP mail inboxes, including sizes, last access times, and more in an easy-to-read-at-a-glance web based interface.
A daemon that provides a method to track generic POP3 or IMAP logins and then email (in future:also block) the user if they exceed the number of accesses per given minutes allowed.