pidgin-osd is an application that uses the xosd library to print various events on the X root window on receiving incoming messages from pidgin. It is based on gaimnosd 0.7 (the last publically available version). It is mostly like the gaimnosd plugin; the only difference is that an implementation for UTF-8 conversion to the current used locale was added.
sim (simple instant messaging) is an IRC client specialized for use with bitlbee. It is based on sic (http://suckless.org). It reads commands from standard input and prints all server output to standard output. It also multiplexes all channel traffic into one output, so you don't have to switch to different channel buffers. sim must be customized by editing its source code to insert the correct username, server, password, and identification information.
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.
Twisted Words provides implementations of a handful of IM protocols, including IRC, MSNP8, OSCAR, TOC, and Jabber. It also comes with a multi-protocol server built around a few simple interfaces, the goal of which is to facilitate implementations of novel servers, clients, and bots. Out of the box, it comes with server that accepts connections over IRC and PB and seeks out installed third-party plugins to support other interfaces (for example, a Nevow LivePage-based Web interface).
licqweb is a Web frontend for licq. It interfaces with the Remote Management Service plugin and uses AJAX to provide real-time communication. It is useful for people who use IMs from multiple locations and want a 'centralised' application that means no more logging off and on, consolidates chat history to the one location, and prevents problems where messages are missed because another IM client received them.
The Off-the-Record (OTR) Messaging proxy is a multi- platform proxy that allows you to have private conversations using the AIM client of your choice. It provides encryption, which prevents someone who intercepts your instant messages from reading them, authentication, which ensures that the correspondent is who you think it is, and perfect forward secrecy, which ensures that no previous conversation is compromised if you lose control of your private keys.