JSONBOT is a remote event-driven framework for building bots that talk JSON to each other over XMPP. This distribution provides bots built on the JSONBOT framework for console, IRC, XMPP for the shell and WWW, and XMPP for the Google App Engine. A plugin infrastructure can be used to write your own functionality.
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.
GZRBOT is a port of GOZERBOT to the Google Application Engine. It is there for its code and reuse of it is highly recommended. A script is available to clone gzrbot and rename it so you can run your own bot off the GZRBOT code. GZRBOT has a plugin system that lets you program your own plugin and provide you a way to add custom functionality to your bot. Both writing commands and reacting on events through callbacks is supported.