Invisionix Systems' portable Instant Messenger (IRSIM) uses PHP and mySQL. This Open Source program interacts with ICQ, MSN, AIM, Yahoo and Jabber IMs. It features database message buffers, login, a contact list, and message input/output windows.
ZSBot is a PHP framework for developing multi-network instant messaging bots and applications.
real-profile is a website that allows users to create personal profiles to link to in their AIM/AOL/ICQ/etc profiles. It is a combination of services provided by sites such as subprofile.com, quizyourfriends.com, livejournal.com, and several other sites.