LarryMessenger is a simple to install and easy to use cross-platform instant messenger client. It has a nice graphical user interface, and allows people to communicate over a LAN with static IP addresses without the need for a central server. Furthermore, it provides functions to query the ICQ and AIM networks.
daim is an IM client and library that supports many features, including add-ins, AIM proxy, buddy icons, chat, direct IM, file transfer, file sharing, send buddy list, and Trillian secureIM. It also supports retrieving News and Stocks, and scripting through Apache BSF. It also supports ICQ, can emulate Apple's iChat client, and supports iChat available messages as well.
Claros inTouch is an AJAX Web mail, instant messenger, address book, and note taker application. The main features are drag and drop support, background attachment uploading, built-in Bayesian spam protection that can identify junk mail on the fly, folder support for the POP3 protocol, compatibility with any POP3/IMAP and SMTP server, operating system independence, support for sending HTML email, and full MIME compatibility. It also features a unique AJAX instant messenger that is capable of talking with a Jabber server.
JClaim is an instant message client, tools, and development framework. It supports AIM, ICQ, Yahoo!, MSN, Jabber, Google Talk, and SMS. The framework can be used for designing your own tools. The UI includes spell checking and a lot more. A Web interface is included for remote access.