CAKE (Key Addressed Crypto Encapsulation) is a bunch of Python and C++ for implementing the CAKE protocol. The CAKE protocol is a protocol in which all messages have source and destination addresses that are public keys. This is in the same way that IP packets have a source and destination address that is an IP address.
MSNgrep is a script to capture MSN Messenger conversations. It uses pylibpcap to sort through MSN's jumble of packets for instant messages, a few status messages, and TypingUser notifications. Using these, it builds up a database of email addresses to MSN server addresses, and local IP addresses. This lets it match up an instant message to the sender's email address, and the receiver's email address.
err is a plugin-based XMPP chatbot designed to be easily deployable, extensible, and maintainable. It is written in Python, and is based on jabberbot and yapsy with some minor modifications to the first one. It has been tested with HipChat and Openfire, but should be compatible with any XMPP/Jabber servers. It can be set up so that a restricted list of persons have administration rights. Dynamic plugin architecture: the bot admin can install/uninstall/enable/disable plugins dynamically just by chatting with the bot. Supports MUCs (chatrooms). Can proxy and route one to one messages to MUC so it can enable simpler XMPP notifiers to be MUC compatible (such as the Jira XMPP notifier). It is easily extensible. It provides an an automatic persistence store per plugin, and a !help command that dynamically generates the documentation from the Python docstrings of the commands. Create a user for the bot on your private XMPP server or a public server like jabber.org. Optionally, you can create a MUC (also called a conference room or chatroom) in which you can interact with the bot.
Ybot is erlang bot software inspired by Github hubot. It supports IRC and XMPP transports and is extensible with plugins. Plugins can be written with Python, Ruby, or shell. It supports IRC chat, XMPP multi user chat, and 37 signals Campfire chat. It can simultaneously run any number of bots on different transports.
Soulseek (http://www.slsknet.org) is a communication and file-sharing system. It is quite similar to Napster: it lets you exchange files, search for files, chat with other users in public and in private, browse their files, and get recommendations for music. SoulSeek for Linux is a GUI client for the system written in Python/wxPython. It includes all the major functionality: chat, searches, and file transfers.