Salut à Toi (or SàT: "Hi to You") is an XMPP/Jabber client with multi-frontends. You can use it on a desktop (Wix), with a console interface (Primitivus), as a command-line tool (jp), or on the Web (Libervia). A plugin architecture is used to make it modular. With SàT, you can perform all the expected XMPP functions (instant messaging, multi-user chat, file transfert, etc.), but you can also use your email client (MUA) to read and send your XMPP messages, play games, do microblogging, pipe Unix command results, make scripts, etc.
Poezio is a console-based client for XMPP, the protocol on which the Jabber IM network is built. Its goal is to let you connect to the network very easily (without having to create an account) and join various chatrooms immediately. It tries to look like the most famous IRC clients (such as weechat and irssi). Many commands are identical and you won't be lost if you already know these clients. Configuration can be done in a configuration file or directly from the client. It embodies the light, fast, geeky, and anonymous spirit of IRC while using a new, powerful, standard, and open protocol.
Scopserv Communicator is an audio/video Internet phone and instant messenger that supports some of the most popular VoIP and instant messaging protocols such as SIP, Jabber (XMPP), AIM/ICQ, MSN, Yahoo! Messenger, and a whole lot of other useful features. ScopServ Communicator is based on the SIP Communicator softphone.
sxmppd is a server for the XMPP (Jabber) chat protocol. While other, functional XMPP servers exist, they are not as simple or have many dependencies. It supports user authentication, SSL, roster management, presence updates and subscriptions, messaging (local users), group chat, and file-based server configuration.
Ibid is a multi-protocol, general purpose, instant messaging chat bot written in Python. It aims for a naturalistic interface rather than strict-syntax commands. Ibid understands many protocols, including IRC, Jabber/XMPP/Google Talk, Campfire, NMDC, and SILC. It also interacts over SMTP, HTTP, and various RPC protocols. Ibid aims to make plugins as easy as possible to write. It ships with a large collection of plugins for looking up information, performing conversions, storing factoids, delivering messages, and much more.