NoxBot is a modular IRC bot that uses the platform independence of PHP. NoxBot is easy to use and features many commands that can be given to the bot over IRC. There are the many available modules. If NoxBot does not provide exactly what you need, then it can be easily implemented as a module. NoxBot tries to stay as RFC-complaint as possible. Some of its features include authentication, module management, a help system, multi-lingual support, timers, a storage system that separates modules, and many more.
LinQ is a full featured, modern Jabber instant messaging client. It is compatible with many other instant messaging clients, like Google Talk, Gaim, Psi, and Meebo. It aims to be fully compliant with XMPP, and to catch up with the latest JEPs. It provides a set of APIs to enable other developers to write their own plugins. Most features are implemented by plugins.