phlyMail is a Webmail and data hosting application. It features IMAP, POP3, SMS, Fax support, a Calendar, Bookmarks, files manager. Multiuser and single user editions available.
NOTICE: Keep in mind that POP3ye is alpha software and by definition it is a long way from finished.
POP3ye is a fully featured web-based e-mail client written in Object Oriented PHP 5. It ony supports the POP3 protocol.
LIMeTool (pronounced like the fruit), is intended to be a simple and easy interface for managing accounts on an integrated Sendmail/LDAP/Cyrus IMAP installation. It's written in PHP and is realitively easy to configure and expand.