Yalst ("yet another live support tool") is a powerful chatting tool that integrates easily with any Web site. The highlights are visitor and operator initiated chats, audio and video chats, visitor monitoring and tracking with alarm functionality, form monitoring, file transfers in both directions during chats, plugin-free co-browsing, marketing tools (push banners, URLs, messages, and customized surveys), ad-tracking of campaigns, conversion tracking, departments, a FAQ database, a customized contact form (if chat is offline), chat between operators, and an application programming interface for deep Web site integration.
twidge is a client for microblogging sites such as Twitter and Identica (identi.ca). It is extremely versatile, can be customized to work the way you want to work, and can be combined with other tools to do just about anything. It can be used interactively from the shell. It is useful directly as-is, and with simple shell aliases can make a highly efficient system to do exactly what you want. It is perfectly capable of being your only client for microblogging. It can also be used in an automated way, via cron(1), or it can even integrate with your email system.
alph implements and analyzes historical and traditional ciphers and codes, such as polyalphabetic, substitutional, and mixed employing human-reconstructable algorithms. It provides a pipe filter interface in order to encrypt and decrypt block text to achieve transparency. The program is meant to be used in conjunction with external programs that transfer data, resulting in transparent encryption or decryption of information. The program can thus be used as a mail filter, IRC filter, IM filter, and so on.
Akeni LAN messenger is a cross-platform instant messenger client. It is a P2P program that works on your LAN without the need of an Internet connection or a dedicated server. The client has an user interface similar to AIM, ICQ, or MSN Messenger. It supports all the standard IM features such as chat, group conference, presence management, file transfer, and emergency alert/notification. Extra features include contact management and optional tabbed chat sessions.